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Ficus cunia is used by many tribes in India to combat several disease conditions such as liver disease, ulcer, dysentery, gynecological disorders and has been reported for the existence of various phenolic compounds. Phenolic compounds are highly spread and broadly dispersed in medicinal plants and are known for several health maintenance abilities. Medicinal plants comprising phenolic compounds display antioxidant and anti-inflammatory abilities which may play a vital role in controlling hypercholesterolemia. Free radicals are responsible for the pathogenesis of chronic diseases. Hypercholesterolemia is supposed to arise from oxidative stress. The purpose of the study was to determine the antioxidant, anti-inflammatory and anti-HMG-CoA reductase potential along with the simultaneous determination of phenolic compounds in hydroalcoholic extract of Ficus cunia fruits. In the current study estimation of total phenol and flavonoid content, in vitro antioxidant, anti-inflammatory and anti-HMG-CoA reductase screening and a simple and consistent high performance liquid chromatography (HPLC) method were established for simultaneous determination of phenolic compounds (gallic acid, catechin, caffeic acid, rutin, ellagic acid and quercetin) in the hydroalcoholic extract of Ficus cunia fruits (HAFC). Total phenolic and total flavonoid contents in the HAFC were found 58.12±3.6 mg gallic acid equivalents/g and 23.01±1.35 mg quercetin equivalents/g, respectively. HAFC showed good antioxidant activity (IC 50 =34.93±2.34 μg/ml for DPPH; IC 50 =49.25±2.3 μg/ml for ABTS). The FRAP and ORAC values of HFAC were found as 87.41±2.98 mg of ascorbic acid equivalents/g and 105±3.82 μM trolox/g extract. Anti-inflammatory activity was significant and increased gradually with concentration. HAFC showed promising inhibition of HMG-CoA reductase (IC 50 =37.50±1.80 μg/ml). The optimized HPLC method was performed for 65 min with detection wavelengths of 254, 278 and 300 nm, gradient elution system on a ZorbaxSB-C 18 Reversed phase column. The developed system was assessed by validation as per ICH guidelines. The results showed that ellagic acid was found in the highest amount (11.34±.01 mg/g) followed by catechin (5.18±.02) and gallic acid (4.23±.05) among the examined phenolic compounds while caffeic acid was not detected. The results of the present study suggest that the Ficus cunia extract has antioxidant, anti-inflammatory potential and is capable of lowering cholesterol levels. The developed RP-HPLC method may be useful for the quality control of plant extracts/herbal products. [Display omitted] • TPC and TFC of hydroalcoholic extract of F. cunia fruits were studied. • Anti-HMG-CoA reductase potential of the extract was evaluated. • Simultaneous determination of phenolic compounds in extracts by RP-HPLC. • Extract showed the great potential of HMG-COA reductase inhibitory activities. • Ellagic acid was found in the highest amount in the extract. [ABSTRACT FROM AUTHOR]

• RP-HPLC method for curcumin and quercetin was developed in rat plasma. • The developed method was validated as per ICH M10 guidelines. • Method was found linear in the concentration range of 2–10 µg/mL. • Recovery above 95% and% RSD less than 2 indicated about accuracy and precision of method. • Absence of interfering peaks at the retention times of curcumin and quercetin indicated method's specificity. Curcumin (CUR) and quercetin (QUE) are the two important flavonoids that possess very good anti-inflammatory, anti-oxidant, antidiabetic, analgesic and anti-cancer activities. Reverse phase high performance liquid chromatography (RP-HPLC) was used to develop a bioanalytical method for simultaneous estimation of both the drugs in the rat's plasma. The method was further validated as per ICH M10 guidelines using C-18 reverse phase column. Fisetin was used as an internal standard. Gradient elution was carried out at a flow rate of 1 mL/min in acetonitrile (ACN) and 2% glacial acetic acid (GAA). The chromatograms of all three phytoconstituents were recorded at detection wavelength of 392 nm. The drugs were extracted from the plasma samples by using protein precipitation method. The retention times (Rts) of fisetin, QUE and CUR were found to be 4.2, 5.5 and 12.1 min respectively. The developed method was found to be linear in the range of 2–10 µg/mL with regression coefficient (r2) of 0.9998 and 0.9993 for QUE and CUR respectively. The percentage recovery of drug more than 95% and percentage relative standard deviation less than 2% among the replicate studies indicated that the method was accurate and precise. Limit of detection (LOD) and limit of quantification (LOQ) in plasma samples were found to be 0.18 and 0.54 µg/mL for QUE and 0.35 and 1 µg/mL for CUR respectively. Further, the stability studies were also carried out at freeze-thaw cycles, short term stability at room temperature. The developed method was found to be robust and passed all the parameters of validation and therefore can be used effectively for estimation of CUR and QUE in the rat plasma. [ABSTRACT FROM AUTHOR]

• Measurement of intestinal permeability and absorptive capacity in the domestic cat. • Quantification of sugars in plasma using liquid chromatography-mass spectrometry. • Simultaneous analysis of lactulose, rhamnose, xylose, and 3-O-methylglucose (3-OMG) • Use of stable isotope labelled 13C standards for each target sugar. A novel method for quantifying the concentration of lactulose, rhamnose, xylose, and 3-O-methylglucose (3-OMG) in cat plasma using liquid chromatography-mass spectrometry (LC-MS) was developed. Domestic male cats (n = 13) were orally dosed with a solution containing the four sugars to test the permeability and absorptive capacity of their intestinal barrier. Plasma samples were taken 3 h later and were prepared with acetonitrile (ACN), dried under N 2, and reconstituted in 90 % ACN with 1 mM ammonium formate. Stable isotope labelled 13C standards for each analyte were used as internal standards. Chromatographic separation was conducted using a Phenomenex Luna NH2 column with a gradient elution system of deionized water and 90 % ACN with 1 mM ammonium formate at 300 µL/min for 13 min total analysis time. Recovery trials were conducted in triplicate over three days with RSD values (%) for each day ranging from 1.2 to 1.4 for lactulose, 5.4 – 6.0 for rhamnose, 3.3 – 5.5 for xylose, and 2.6 – 5.6 for 3-OMG. Inter-day variations for each analyte were not different (p > 0.05). Limit of detection and quantification were 0.2 and 0.7 µg/mL for lactulose, 0.8 and 2.4 µg/mL for rhamnose, 0.6 and 1.8 µg/mL for xylose, and 0.3 and 1.1 µg/mL for 3-OMG, respectively. Plasma sugar concentrations recovered from cats were above the limit of quantification and below the highest calibration standard, validating the use of this method to test intestinal permeability and absorptive capacity in cats. [ABSTRACT FROM AUTHOR]

• An LC-MS/MS method was optimized for cardiovascular drugs in dried blood spots (DBS). • Drugs in DBS were simply extracted with organic solvents in two-step protein precipitation. • This method was fully validated for linearity, matrix effect, accuracy, and stability. • Drug distribution within spots was analyzed using punched discs. • Feasibility of accuracy-based analysis for cardiovascular drugs in DBS was proposed. Dried Blood Spots (DBS) revolutionize therapeutic drug monitoring using LC-MS for the precise quantification of cardiovascular drugs (CDs), enabling personalized treatment adapted to patient-specific pharmacokinetics with minimal invasiveness. This study aims to achieve simultaneous quantification of eight CDs in DBS, overcoming physicochemical challenges. A two-step protein precipitation method was used for simple and precise sample preparation. The drugs were analyzed using LC-MS/MS in ESI positive-ion mode, showing high sensitivity and linearity, with a correlation coefficient (r2) exceeding 0.999, after being separated on a reversed-phase chromatography by gradient elution of DW-acetonitrile containing 0.1 % formic acid + 2 mM ammonium formate. The validation results indicate good selectivity, with no observed matrix effect and carry-over. The intra- and inter-day accuracy and precision were within 6 % for most drugs, except for digoxin and deslanoside at low therapeutic levels where the variation was within 20 %. Stability tests confirmed suitable DBS handling and storage conditions, indicating drug stability for at least 30 days at room temperature. The analysis of whole spot has demonstrated remarkable precision and reliability in all target drugs. The analysis of 3 mm internal diameter discs, punched in and out of DBS, presumed to contain 3 µL of blood, showed acceptable accuracy for most drugs, with less polar drugs like digoxin and deslanoside showing lower accuracy, indicating a need for further correction due to non-uniform drug distribution. Consequently, the developed LC-MS/MS method enables the quantification of multiple CDs in a single DBS analysis, while suggesting the potential for accuracy-based analysis. [ABSTRACT FROM AUTHOR]

• The QuEChERS pretreatment method with LC-MS was used to monitor liver cancer drug concentrations in blood. • This simple, rapid, and efficient method detected 7 tyrosine kinase inhibitors in plasma within four minutes. • Most of the drugs selected in this study are second-line drugs. Tyrosine kinase inhibitors (TKIs) are commonly used to treat various cancers. Literature suggests that the blood concentration of TKIs strongly correlates with their efficacy and adverse effects. Therefore, establishing a Therapeutic Drug Monitoring (TDM) methodology for TKI drugs is crucial to improving their clinical efficacy and minimizing the treatment-related adverse effects. However, quantifying their concentrations in the plasma using existing methods to avoid potential toxicity is challenging. Herein, seven TKIs, namely sorafenib tosylate, axitinib, erlotinib, cediranib, brivanib, linifanib, and golvatinib, were successfully analyzed in human plasma by following a quick, easy, cheap, effective, rugged, and safe (QuEChERS) pretreatment method combined with ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). Briefly, biological samples were extracted using 1 mL of methanol, followed by the sequential addition of 250 mg of anhydrous magnesium sulfate and 25 mg of N-propylethylenediamine (PSA) for salinization and purification by adsorption, respectively. In this study, dovitinib was used as the internal standard. The seven TKIs were detected by the gradient elution method for 4 min in the positive ion electrospray mode. The mobile phase comprised methanol (phase A) and 0.1 % aqueous formic acid solution (phase B) on the Agilent Zorbax RRHD Stablebond Aq, (2.1 × 50 mm; 1.8 μm). Brivanib, linifanib, axitinib, sorafenib tosylate, and golvatinib exhibited good linearity in the range of 5–500 ng/mL, and erlotinib and cediranib exhibited good linearity in the range of 10–1000 ng/mL, with linear correlation coefficients (R2) ≥ 0.99. The limits of detection and quantification were 0.60–0.18 ng/mL and 5–10 ng/mL, respectively. The intraday and interday accuracy values ranged from −6.12 % to 7.31 %, with a precision (RSD) of ≤ 10.57 %. The method was rapid, accurate, specific, simple, reproducible, and suitable for the quantitative determination of the seven TKIs in human plasma. [ABSTRACT FROM AUTHOR]

Oligosaccharides constitute fundamental components in numerous traditional Chinese medicines (TCMs). Conventional chromatographic methods for natural product analysis are not suitable for oligosaccharides due to their large polarity and structural similarity. Herein, an ultra-high performance liquid chromatography with charged aerosol detector (UHPLC-CAD) method was developed for the profiling of oligosaccharides using 9 neutral (DP3-DP11) reference oligosaccharides. Various factors, including columns, mobile phase, elution conditions, flow rate, and column temperature were systematically examined. Optimal separation was achieved using an Amide column with gradient elution within 18 min, at 0.5 mL/min flow rate and 30°C column temperature. Moreover, an ultra-high-performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UHPLC-Q-TOF/MS) method was also optimized to provide structural information. The developed method was applied to detect oligosaccharides in several TCMs, including Morindae Officinalis Radix (MOR), Ziziphi Spinosae Semen (ZSS), Menthae Haplocalycis Herba (MHH) and Chrysanthemi Indici Flos (CIF), revealing 9 and 16 oligosaccharides being uncovered from MHH and CIF respectively for the first time. This study presents a versatile UHPLC-CAD and UHPLC-Q-TOF/MS method with the potential for advancing oligosaccharides discovery and contributing to the quality analysis of TCMs. • A universal method for profiling oligosaccharides in TCMs was developed. • The relative content of oligosaccharides in TCMs was investigated by UHPLC-CAD. • Nine and sixteen oligosaccharides were uncovered from MHH and CIF, respectively. [ABSTRACT FROM AUTHOR]

Antimicrobials, particularly antibiotics, are among the most common classes of drugs reported as substandard and falsified (SF) in developing countries. Therefore, it is important to develop simple and affordable analytical methods for the quality control of antimicrobial medicines. In this study, a liquid chromatographic method with ultraviolet detection (LC-UV) was developed and validated for the screening and quantification of 13 antimicrobial medicines and one beta-lactamase inhibitor in pharmaceutical formulations. LC separation was carried out on a Kinetex C18 column (150 mm × 4.6 mm, 2.6 µm) with gradient elution. The mobile phase consisted of mixtures of acetonitrile-water-10 mM phosphate buffer pH 3.5 at ratios of 3:92:5, v/v/v for mobile phase A and 50:45:5, v/v/v for mobile phase B with a flow rate of 0.5 mL/min. The screening method was intended for confirmation of the identity of the actives and validated for specificity and robustness, whereas the quantification method (using only a different detection wavelength) was further validated in terms of linearity, accuracy, sensitivity and precision (repeatability, intermediate precision). For all compounds, the method was found to be linear (r2 > 0.999), precise (%RSD < 1%), accurate (% recovery of 98–102%), sensitive, specific and robust. The developed LC method was successfully applied for the identification and assay of 12 antimicrobial samples from Ethiopia. Among the 12 samples analyzed, one (8.3%) product was confirmed to be falsified. [Display omitted] • Novel LC-UV method for screening and quantification of antimicrobial medicines. • Antimicrobial drugs mostly prone to counterfeiting were included in this study. • Successfully validated according to the ICH guidelines. • Method was applied to analyse suspicious samples. [ABSTRACT FROM AUTHOR]

• Rapid and simultaneous determination of 6 volatile fatty acids (VFAs) via HPLC-MS/MS. • The derivatisation method solves the problems of fatty acids in the detection process. • High throughput analysis of samples can be determined high sensitivity and accuracy. • VFAs can be accurately quantified using only microsamples (faeces, serum and urine). A stable isotope dilution-liquid chromatography tandem mass spectrometry method based on a low-temperature derivatization strategy with 3-nitrophenylhydrazine (3-NPH) was developed for the determination of six volatile fatty acids (VFAs) in serum, urine, and feces. Ice acetonitrile was used to precipitate proteins and extract the target analytes. The extract was derivatized with 3-NPH methanol solution at 4 °C. BEH C8 (1.7 μm, 2.1 × 100 mm) column was used for chromatographic separation, and acetonitrile–water (both containing 0.01 % formic acid) were used as the mobile phase with a gradient elution of 10 min. Electrospray ionization source (ESI) in negative ion multiple reaction monitoring (MRM) mode were used for analyte detection. The regression coefficients R2 of the calibration curves for the six VFAs were in the range of 0.9963–0.9994, and the LOQs were in the range of 0.02–0.5 μg mL−1, with the recoveries in the range of 85.3–104.3 %, and the intra- and inter-day precision in the range of 1.8–9.1 %. The method is simple, accurate and reliable, and has been applied in the sensitive determination of VFAs in complex biological samples. [ABSTRACT FROM AUTHOR]

• Atenolol and metoprolol are the preferred drugs in the treatment of hypertension and heart failure. • Importance of assessing intestinal absorption and permeability of orally administered drugs by in-situ perfusion studies. • Use of HPLC as an analytical method in quantification and drug quality control. • Development of an HPLC method that simultaneously detects atenolol, metoprolol, and phenol red (zero permeability marker). Single-pass intestinal perfusion (SPIP) method is a widely used experimental model to determine the intestinal permeability of drugs. These studies are performed in the presence of a reference standard (metoprolol, MT) and a zero permeability marker (phenol red, PR). Therefore, it is important to develop a validated method for simultaneous determination of the investigated compound along with MT and PR. The aim of this study was to develop a reversed phase high-performance liquid chromatography (RP-HPLC) method with UV-detection for the simultaneous determination of atenolol (ATN), MT, and PR in the perfusion medium used in SPIP experiments. Separation of compounds were performed using an InertSustain C18 (250 × 4.6 mm, 5 µm) HPLC column at 35 °C. The mobile phase was a mixture of acetonitrile and phosphate buffer (pH 7.0, 12.5 mM) in gradient elution, and was delivered at a flow rate of 1 mL/min. The acetonitrile ratio of the mobile phase increased linearly from 10 to 35 % over 15 min. The injection volume was 20 µL, and ATN, MT and PR were detected at 224 nm. The retention times under optimum HPLC conditions were 5.028 min, 12.401 min, and 13.507 min for ATN, MT and PR, respectively. The developed RP-HPLC method was validated for selectivity, specificity, calibration curve and range, accuracy and precision, carry-over effect, stability, reinjection reproducibility, recovery and robustness. The method was linear for ATN (0.76–50 μg/mL), MT (1.14–50 μg/mL), and PR (0.47–20 μg/mL) with determination coefficients of 0.9999, 0.9994 and 0.9998, respectively. The results obtained for all validation parameters of the developed RP-HPLC method met the required limits of the ICH M10 Guideline. [ABSTRACT FROM AUTHOR]

Alternative blood sampling strategy can enhance the application of therapeutic drug monitoring (TDM), then improve precision therapy and medication compliance. In developing nations, alternative sampling strategy that allows self-sampling and room temperature transport is especially important. This study validates the use of dried blood spot (DBS) and dried plasma spot (DPS) sampling along with liquid chromatography–tandem mass spectrometry (LC–MS/MS) for analyzing seven common antiepileptic drugs (AEDs) (phenytoin, lamotrigine, levetiracetam, topiramate, carbamazepine, oxcarbazepine and its active metabolite 10,11-dihydro-10-hydroxy carbamazepine) and evaluates their applicability to clinical practice. Following simple protein precipitation with acetonitrile, the AEDs were separated on a C18 column by gradient elution with a mobile phase consisting of acetonitrile–water–0.1% formic acid at a flow rate of 0.65 mL/min. The method provided linear analysis over the tested concentration ranges, with a total run time of 7 min. Intra- and inter-assay precision for all quality controls were ≤12% with accuracies of 85.9%–113%. The average extraction efficiencies were 69.0%–92.4% for DBS and 65.9%–96.5% for DPS, and no significant matrix effects were observed. The AEDs were stable in all samples for seven days at room temprature and 40°C. There was good correlation between the dry and wet plasma concentrations with greater accuracy for DPS compared to DBS indicating that alternative sampling strategy using DBS and DPS are suitable for monitoring the concentrations of AEDs with satisfied performance and logistical advantages. • Development and validation of a LC–MS/MS method for the quantification of seven antiepileptic drugs in dried microsamples. • Demonstration of the method's applicability in clinical practice by comparing the results with traditional plasma analyses. • An affirmation that the antiepileptic drug concentrations in dried samples are highly consistent with plasma levels. Dried plasma spot-based analyses showcasing higher accuracy than dried blood spot-based analyses. [ABSTRACT FROM AUTHOR]

BGT-002, a new type of ATP-citrate lyase inhibitor, is a promising therapeutic for treatment of hypercholesterolemia. After an oral administration of BGT-002 to subjects, it underwent extensive metabolism and an acyl monoglucuronide (ZM326E-M2) on 1- carboxylic acid group was the major circulating metabolite. In this study, an LC-MS/MS method was developed and validated for the simultaneous determination of BGT-002 and ZM326E-M2 in plasma and the evaluation of their pharmacokinetic characteristics in humans. After extraction from the plasma by acetonitrile-induced protein precipitation, the analytes were separated on a Waters ACQUITY UPLC® BEH C 18 column using acetonitrile and 2 mM ammonium acetate containing 0.1% formic acid as the mobile phase for gradient elution. Negative electrospray ionization was performed using multiple reaction monitoring (MRM) of m/z 501.3→325.4 for ZM326E-M2 and m/z 507.3→331.2 for D 6 -ZM326E-M2, and pseudo-MRM of m/z 325.3→325.3 for BGT-002 and m/z 331.3→331.3 for D 6 -ZM326E, respectively. The method was validated with respect to accuracy, precision, linearity, stability, selectivity, matrix effect, and recovery. The analytical range in human plasma was linear over a concentration range of 0.0500–50.0 μg/mL for BGT-002 and 0.0100–10.0 μg/mL for ZM326E-M2. The pharmacokinetic results showed that after a single oral administration of 100 mg BGT-002, the parent drug was rapidly absorbed with a mean time to peak concentration (t max) of 1.13 h, compared with BGT-002, the t max (4.00 h) of ZM326E-M2 was significantly delayed. The peak concentration and plasma exposure of ZM326E-M2 were about 14.1% and 19.5% of the parent drug, suggesting that attention should be paid to the safety and efficacy of ZM326E-M2 in clinical research. • BGT-002 is a new type of ATP-citrate lyase inhibitor developed for hypercholesterolemia therapy • First LC-MS/MS method for the simultaneous quantification of BGT-002 and its acyl glucuronide metabolite in human plasma. • The developed method was successfully applied to a clinical pharmacokinetic study. [ABSTRACT FROM AUTHOR]

• A fast, sensitive and selective method has been developed for the analysis of polypeptide antibiotics. • HRMS is essential to overcome interferences from endogenous matrix components. • Multiple charged ions are selected for polypeptide HRMS detection. • This reliable method is very suitable for analyzing large series of samples. A confirmatory method for the determination of polypeptide antibiotics (bacitracin, colistin, and polymyxin B) in muscle samples has been developed. Extraction is performed with acidified methanol, and a clean-up step by solid-phase extraction with polymeric cartridges is applied. Separation by ultra-high performance liquid chromatography (UHPLC) is carried out using a solid core C18 column and gradient elution with water/acetonitrile containing 0.2% formic acid. High-resolution mass spectrometry (HRMS) (Q-Orbitrap) detection using different working modes has proved to be highly advantageous in eliminating interfering signals from endogenous matrix components. The analytical method has been successfully validated according to Commission Regulation 2021/808/EU and is currently used in a public health laboratory involved in veterinary medicines residue surveillance activities. [ABSTRACT FROM AUTHOR]

• An LC-MS/MS method for simultaneous drug quantification was optimized. • The method covers 1st–3rd-generation antiepileptic drugs in a single analysis. • Cost-effective sample preparation by minimizing isotope-labeled internal standards. • The method was fully validated and stability was tested. • Reliability was confirmed in lipid-, glucose-, and protein-rich samples. This study aims to establish an LC-MS/MS method to simultaneously analyze 11 antiepileptic drugs with a particular focus on maintaining accuracy while reducing the number of isotope-labeled internal standards employed for cost-effectiveness. By applying a water/acetonitrile gradient elution containing 0.1 % formic acid and 2 mM ammonium formate as the mobile phase, optimal sensitivity for the target drugs could be obtained in positive ESI mode in LC-MS/MS. After optimizing various extraction techniques, extraction with 70 % acetonitrile was selected as it provided good recoveries (>93 %) for all targets without matrix effects. Accuracies within 3 % were achieved from the combination of six internal standards, while accuracies of 5 % and 10 % were obtained by reducing the number of internal standards to four and two, respectively, for more economical analysis. The accuracy of the established method was maintained in hyperglycemia, hyperlipidemia, and hyperalbuminemia sera, suggesting that it can be successfully applied to individual serum samples with various properties. [ABSTRACT FROM AUTHOR]

Nitrite (NO 2 −) and nitrate (NO 3 −) can be produced in the distribution systems of chloraminated drinking water due to the nitrification of ammonia. The most applied inorganic chloramine for this purpose, namely monochloramine (NH 2 Cl), is also released into aquatic environments from water treatment plants' effluent and within industrial waste streams. Within the treatment process, the continuous monitoring of disinfectant levels is necessary to limit the harmful disinfectant by-product (DBP) formation. Currently, NH 2 Cl can interfere with nutrient analysis in water samples, and there are no analytical techniques available for the simultaneous analysis of NH 2 Cl, NO 2 −, and NO 3 −. A green analytical method based on mixed-mode ion chromatography, specifically ion exchange and ion exclusion modes, was developed for the simultaneous separation and detection of NH 2 Cl, NO 2 −, and NO 3 −. The separation was achieved using a Dionex IonPac AG15 column guard column and a step gradient elution involving deionized water and 120.0 mM NaCl. The method was developed using a benchtop HPLC with a custom-made multi-wavelength UV absorbance detector with a 50-mm flow cell to enable the sensitive detection of NH 2 Cl, NO 2 −, and NO 3 − at 240 nm, 220 nm, and 215 nm, respectively. The developed method was then transferred to a portable ion chromatography (IC) system, the Aquamonitrix analyser. The total run time was less than 10 min for both systems. The benchtop HPLC method had a limit of detection (LOD) of 0.07 μg mL−1 as Cl 2 for NH 2 Cl, 0.01 μg mL−1 for NO 2 −, and 0.03 μg mL−1 for NO 3 −. The LODs obtained using the portable Aquamonitrix analyser were found to be 0.36 μg mL−1 as Cl 2 , 0.02 μg mL−1, and 0.11 μg mL−1 for NH 2 Cl, NO 2 −, and NO 3 −, respectively. Excellent linearity (r ≥ 0.9999) was achieved using the portable analyser over the studied concentration ranges. The developed system was applied to the analysis of spiked municipal drinking water samples and showed excellent repeatability for the three analytes at three different concentration levels (RSD of triplicate recovery experiments ≤ 1.9 %). Moreover, the variation in retention time was negligible for the three target analytes with RSD ≤ 0.8 % over 12 runs. We are reporting the first ion chromatographic method for the simultaneous separation and detection of NH 2 Cl, NO 2 −, and NO 3 − in water samples. The monitoring of NH 2 Cl, NO 2 −, and NO 3 − is critical for the determination of disinfectant dosing, water quality, and nitrification status. The developed method can be applied using a benchtop HPLC or via the portable automated IC system to monitor for the three target compounds analysis in water treatment plants. [Display omitted] • Mixed-mode ion chromatography for the simultaneous separation of monochloramine, nitrite, and nitrate. • The separation method was transferred to a portable ion chromatography system. • The method was applied to the analysis of tap water samples. • The portable analyser demonstrates potential for real-time monitoring of municipal water supplies. [ABSTRACT FROM AUTHOR]

Multicomponent drugs are medications that combine two or more active pharmaceutical ingredients in a single dosage form. These dosage forms improve the patient compliance, reduce the risk of drug interactions, and simplify dosing regimens. However, quality control of these multicomponent dosage forms can be challenging, especially if the final product contains four or more ingredients that are active (comprise stabilizers, preservatives, excipients, and other components). This problem can be more pronounced if the excipients can interfere with the analysis. In this work, a stability indicating assay method was developed and validated (according to the ICH International Guidelines) for the simultaneous determination of hydroquinone (HQ), tretinoin (TRT), hydrocortisone (HCA), butylated hydroxytoluene (BHT), methyl paraben (MP) and propyl paraben (PP) in commercially available pharmaceutical creams. The proposed method is based on gradient elution using X-Bridge C18 (150 × 4.6 mm, 5 µm) column with a flow rate of 1 mL/min. The linear ranges (μg/mL) were 240–560 for HQ, 24–56 for MP, 132–308 for HCA, 6–14 for PP, 12–28 for BHT, 6.6–15 for TRT. During the validation process, the intra- and interday precision and trueness (evaluated as recovery) were found to be below 2.0% and between 100–102%, respectively. System suitability tests (SST) allow validating the herein proposed procedure specifically for pharmaceutical and industrial applications. SST test shows that the reported procedure fulfill with the Guidelines, allowing excellent separation of the analytes with very sensitive, accurate (precise and true) and reproducible quantitation of each analytes. The method was successfully applied in forced degradation studies of the six analytes. Specifically, acid degradation slightly affected HCA and BHT (91% recovery), while alkaline degradation drastically reduced HCA recovery (5.5%) and moderately affected BHT (85%). Photodegradation primarily influenced TRT quantity, and oxidative degradation intensified the BHT peak (130%). [Display omitted] • Validated HPLC method for the quantitation of hydroquinone, tretinoin, hydrocortisone, butylated hydroxytoluene and parabens. • Innovative analytical approach for multicomponent formulations. • Practical application for drug quality control in cream dosage form. • First tool to successfully quantify up to 6 components simultaneously in a topical formulation. • AGREEprep and BAGI evaluation of the proposed method. [ABSTRACT FROM AUTHOR]

Catalytic reactions play a central role in chemical production, wherein the strength of the catalyst support is key to long-term stable operation. Simple and efficient strength enhancement methods for heterogeneous catalysis have received significant attention. Herein, we developed a variable-temperature gradient elution technology for low-carbon alcohols to improve the crushing strength of microspheres prepared using the sol–gel method in a microfluidic system. Based on gel fiber growth and rearrangement utilizing the hydrogen-bonding effect between low-carbon alcohols and pseudo-boehmite, the pore structure and fiber network can be reconstructed. Low-carbon alcohols with strong hydrogen bonds and low steric hindrance are more conducive to the formation of short fibers when constructing a dense gel network coordinated with higher alcohols. By combining long and short fiber cross-linked networks, the crushing strength of microspheres is significantly improved, and a dense pore structure with a small pore volume forms. After gradient elution, a crushing strength of up to 71.78 N/mm2 can be achieved with a high specific surface area of 254.27 m2/g, which significantly exceeds that of commercial alumina supports with the same pore volume. This efficient method provides an important solution for the long-term, stable operation of catalysts. [Display omitted] • Regulate fiber growth by hydrogen bonding effect and steric hindrance of alcohol. • Reveal the relationship between skeleton structure and crushing strength. • An efficient method for preparation of ultra-high strength microspheres. [ABSTRACT FROM AUTHOR]

• A model-based approach was shown for gradient elution liquid-liquid chromatography. • The elution profiles of the modifier and solutes were described with a stage model. • Only a few experiments were necessary for model parameter determination. • Pre-selected gradient shapes were optimized by maximizing productivity and yield. • The approach is applicable for systems with constant stationary phase composition. Liquid-liquid chromatography (LLC) is a separation technique that utilizes a biphasic solvent system as the mobile and stationary phases. The components are separated solely due to their different distributions between the two liquid phases. Gradient change in the mobile phase composition during the chromatographic process is a powerful method for improving the resolution of separation or shortening the process time. Gradient elution readily applies to LLC with biphasic solvent systems in which the stationary phase composition remains nearly constant when the mobile phase composition changes. This work proposes a model-based approach to optimize gradients in LLC and circumvent tedious trial-and-error experiments. The solutes' distribution constant depends on the mobile phase composition. Thus, the distribution constants were described as a function of the content of one of the solvents (= modifier) in the mobile phase. The dispersive and mass-transfer effects in the tubing and the column are modeled with a stage model. Only a few experiments are required to determine the model parameters. After the validation of the model and its parameters, the model can be used for LLC gradient optimization. The proposed approach was demonstrated for a gradient LLC separation of a mixture of four cannabinoids. Two different gradient shapes, one-step and linear gradient, were considered. For a pre-selected minimal purity requirement, the gradient was optimized for maximum process efficiency, defined as the product of productivity and yield. An experiment conducted with the optimized gradient conditions was in good agreement with the simulation, showing the potential of the proposed method. [ABSTRACT FROM AUTHOR]

• A sensitive method was developed for letrozole and its carbinol metabolite in mouse plasma. • Limited sample volumes allow implementation in large-scale pharmacokinetic studies. • Letrozole levels in plasma are formulation- and strain-dependent. A liquid chromatography - electrospray ionization-mass spectrometry (LC-ESI-MS) method was developed for the quantification of letrozole, a third-generation aromatase inhibitor, and its main carbinol metabolite (CM) in support of murine pharmacokinetic studies. Using polarity switching, simultaneous ESI-MS measurement of letrozole and CM was achieved in positive and negative mode, respectively. The assay procedure involved a one-step protein precipitation and extraction of all analytes from mouse plasma requiring only 5 μL of sample. Separation was optimized on an Accucore aQ column with gradient elution at a flow rate of 0.4 mL/min in 5 min. Two calibration curves per day over four consecutive measurement days showed satisfactory linear responses (r 2 > 0.99) over concentration ranges of 5–1000 ng/mL and 20–2000 ng/mL for letrozole and CM, respectively. No matrix effect was found, and the mean extraction recoveries were 103–108 % for letrozole and 99.8–107 % for CM. Precision and accuracy within a single run and over four consecutive measurement days were verified to be within acceptable limits. Application of the developed method to preclinical pharmacokinetic studies in mice receiving oral letrozole at a dose 1 or 10 mg/kg revealed that the systemic exposure to letrozole was dose-, formulation-, and strain-dependent. These findings may inform the future design of preclinical studies aimed at refining the pharmacological profile of this clinically important drug. [ABSTRACT FROM AUTHOR]

[Display omitted] • Extraction procedure by VAMS and UHPLC-MS/MS method for lyso-Gb3 quantification have been developed. • The extraction method has been validated according to European Medicine Agency (EMA) guidelines. • The developed method was successfully applied to real fingerprick blood VAMS samples. • Lyso-Gb3 concentration found in VAMS and in plasma were compared. • HTC impact and blood VAMS sample stability were evaluated. A volumetric absorptive microsampling (VAMS) combined with UHPLC-MS/MS method was validated for the analysis of lyso-Gb3 in capillary blood. Lyso-Gb3, a biomarker for Fabry disease (FD), was extracted from VAMS device with methanol/acetonitrile/water mixture, in a temperature-controlled ultrasonic bath and the solution was analysed on a Kinetex C18 in gradient elution with MRM detection. The VAMS method was fully validated according to EMA guidelines. No hematocrit effect was observed over a range of 20–70 %. The method showed linearity from 0.25 to 100.00 ng/mL, the lower limit of quantitation was 0.25 ng/mL, both precision and accuracy were ≤ 15 % and the average extraction recovery was 94.6 %. The VAMS UHPLC-MS/MS method was successfully compared with a reference plasma method in a series of 13 Fabry patients and 12 healthy volunteers. This is the first validated UHPLC-MRM VAMS-based method, hematocrit-independent, for capillary blood lyso-Gb3 quantification in FD patients. [ABSTRACT FROM AUTHOR]

Omadacycline is the first aminomethyl-tetracycline variety to successfully enter clinical applications. To support regular therapeutic drug monitoring (TDM) in clinical practice, an ultra-high-performance liquid chromatography coupled with tandem mass spectrometry (UPLC-MS/MS) method was developed that would allow omadacycline quantification in human serum. Proteins were precipitated from serum samples using methanol. Tigecycline was used as the internal standard. Mobile phase A was formic acid in water (0.1% v /v) and mobile phase B was methanol. UPLC-MS/MS was performed for analyte separation using a gradient elution program at a flow rate of 0.3 mL/min and a total run time of 5 min. The chromatography column was a ZORBAX PRHD SB-Aq (3 × 50 mm, 1.8 μm, Agilent, USA). The multiple reaction monitoring transitions at m / z = 557.4/470.3 and 586.5/513.3 were selected for omadacycline and tigecycline in the positive mode, respectively. The validated curve ranges were 0.5–25.0 μg/mL. This method exhibited acceptable selectivity, matrix effects, and recovery. The inter- and intra-run accuracies ranged from 93.5% to 114.8%, and the inter- and intra-run precisions were between 1.29% and 5.55%. The LC-MS/MS method provided a simple, specific, and rapid quantification of omadacycline in the serum of patients with pulmonary infection. [ABSTRACT FROM AUTHOR]

Colistin is a last-resort antibiotic used for treating infections caused by carbapenem-resistant Gram-negative bacteria, particularly in critically patients, nevertheless its therapeutic window is narrow, and requires monitoring. A determination method suitable for clinical detection is conducive to ensure its efficacy and safety of patients with severe infection. We developed and validated a concise and accurate high-performance liquid chromatography-tandem mass spectrometry method for the determination of colistin A and B in human plasma. We used a Kinetex C18 column (50 mm × 2.1 mm, 2.6 μm) with acetonitrile (containing 0.1% formic acid) as the protein precipitant and water (containing 0.2% formic acid and 5 mmol/L ammonium formate) - acetonitrile (containing 0.2% formic acid) as the gradient elution. The calibration curves were linear over concentration ranges of 0.06–4.00 μg/mL (colistin A) and 0.1–7.0 μg/mL (colistin B). The precision, accuracy, matrix effect, extraction recovery, and stability were all validated. This method was applied to the therapeutic drug monitoring for 50 critically ill patients. The trough, peak, and average steady-state concentrations of these patients were 0.8 ± 0.4, 1.4 ± 0.5, and 1.0 ± 0.4 μg/mL, respectively. And the concentrations of colistin in human plasma were closely related to the patient's renal function. • A novel method for determining colistin A and B in human plasma by liquid chromatography-tandem mass spectrometry. • The pretreatment method in this method involved protein precipitation using acetonitrile containing 0.1% formic acid. • The retention time for colistin in this method is 1.8 min using gradient elution procedures. • Our results showed that the concentrations of colistin were closely related to the patient's kidney function. [ABSTRACT FROM AUTHOR]

Liquid chromatography tandem mass spectrometry (LC-MS/MS) is a highly selective and sensitive method for the quantification of kinase inhibitors, yet not widely available in clinical routine for therapeutic drug monitoring (TDM). To provide a more accessible alternative, a high-performance liquid chromatography method with ultraviolet/diode array detection (HPLC-UV/DAD) to quantify cabozantinib, dabrafenib, nilotinib and osimertinib, was developed and validated. Results were compared to LC-MS/MS. After liquid–liquid-extraction and reconstitution of the residue in 20 mM potassium dihydrogen phosphate (KH2PO4) (pH4.6), acetonitrile and methanol (50:25:25,v/v/v), chromatographic separation was achieved in 20.0 min using a Luna® C18(2)-HST column (100 × 2 mm, 2.5 μm), protected by a C18 guard column (4 × 2 mm) (column temperature: 30 °C, autosampler: 10 °C). Mobile phase A and B consisted of 20 mM KH2PO4 (pH4.9) and acetonitrile (9:1,v/v) and acetonitrile:20 mM KH2PO4 (pH4.9) (7:3,v/v), respectively. Gradient elution was performed at 200 µL/min. Analytes were quantified at 250, 280 and 330 nm, using sorafenib as internal standard. Calibration curves were linear (35–2,000 ng/mL). Method validation assays met requirements by U.S. Food and Drug Administration and European Medicines Agency. Compared to the more sensitive and specific LC-MS/MS, HPLC-UV/DAD showed a good correlation and a strong positive association (Kendall's tau 0.811¬–0.963, p < 0.05). Bland-Altman-plots revealed 100% (cabozantinib), 98.6% (dabrafenib), 98.6% (nilotinib) and 96.2% (osimertinib) of relative differences inside the limits of agreement. Regulatory agency criteria for sample reanalysis and cross validation were met (±20%-criterion:100% (cabozantinib), 94.3% (dabrafenib), 92% (nilotinib) and 84.6% (osimertinib). The developed HPLC-UV/DAD method is "fit-for-TDM" in clinical routine and serves as a genuine alternative to LC-MS/MS. [ABSTRACT FROM AUTHOR]

• Leaves of L. glaucescens has a high antioxidant activity. • L. glaucescens has a high concentration of phenolic compounds. • Phenolic compounds responsible for the antioxidant activity of L. glaucescens • Epicatechin, quercetin 3- O -rhamnoside and kaempferol were isolated Litsea glaucescens is a native plant from Mexico and Central America known as laurel, and they leaves are commonly used as food seasoning and traditional medicine, however, there is not enough information about its biological activities, as antioxidant and the compounds responsible of this activity. The antioxidant activity and the total phenolic content of a methanolic extract of L. glaucescens leaves (LGE) and a series of twelve chromatographic fractions (I-XII) obtained through a polarity gradient elution are reported in this work. In all the cases a concentration-response was observed since the DPPH inhibition increases (p≤0.05) as a function of the concentration. Nevertheless, the most polar fractions XI and XII were the most effective of the series (100 µg/mL=93 and 91%, 50 µg/mL= 93 and 91%, 25 µg/mL =92 and 87% and 12.5 µg/mL=85 and 53% of radical inhibition, respectively). The results of the FRAP assay confirmed that XI and XII have the highest antioxidant activity (7994.06 and 5011.03 µmol Fe(II)/g, respectively) and the total phenolic content, evaluated by the Folin-Ciocalteu method, was also the highest in both fractions (462.9 and 347.5 mg GAE/g of dry weight, respectively). In addition, epicatechin, was isolated from XI, whereas quercitrin and kaempferol were obtained from XII by flash chromatography and their structures were elucidated through HPLC-ESI-MS and NMR spectroscopy. Then, it is possible to infer that these phenolic compounds are the main responsible for the antioxidant activity of L. glaucescens. Our study provides information that may be useful for the use of this natural product in food and pharmaceutical formulations. [ABSTRACT FROM AUTHOR]

• Racemic imprinting concept for chiral MIP preparation is introduced. • Enantioselective reuptake of S -KTP on racemic imprinted polymer is achieved. • RS -MIP and S -MIP binding sites were characterized using scatchard plot. • Chiral separation of racemic KTP was achieved on an RS -MIP packed SPE cartridge. This work presented a novel racemic imprinting process employing the chiral properties of chitosan monomer. The preparation of racemic ketoprofen (RS -KTP) imprinted polymer (RS -MIP) was conducted using glutaraldehyde as a crosslinker. The nature of elution solvent affected the % desorption ratio suggesting a heterogenous nature of the formed binding sites. Good imprinting was indicated by an imprinting factor of 3.50 for S -KTP. The enantioselectivity of the RS -MIP was indicated by enantioselectivity coefficient of 2.31 and % enantiomeric excess (% ee) of 28.55%. A SPE cartridge packed with RS -MIP enabled resolution of RS -KTP using gradient elution solvent system. Scatchard plot revealed two binding sites types of different affinity towards S -KTP and density observed for the RS -MIP. The binding capacity of RS -MIP showed observed dependence on the % ee of S -KTP indicating its enantioselectivity. The success of using racemic template for the preparation of enantioselective MIP brings a new possibility to achieve enantioseparation of racemic mixtures having very expensive or unavailable pure enantiomers. [ABSTRACT FROM AUTHOR]

The P. heterophylla and its adulterants were identified by HPLC-CAD fingerprint of sucrose and oligosaccharides in P. heterophylla. The improved quantitative analysis of multi-components with a single marker (iQAMS) was further established for simultaneous determinations of sucrose and oligosaccharides in P. heterophylla. The HPLC-CAD fingerprint and similarity coefficients between P. heterophylla and its adulterants showed significant differences. The relative errors (REs) between iQAMS method and external standard method (ESM) were below 3.00%, but significant difference was shown between iQAMS (different marker for whole program with gradient elution) and QAMS (one marker for whole program with gradient elution), indicating that QAMS method should be improved, especially for gradient elution which influence the response of analytes. The accuracy, precision, reproducibility, and stability of this method were validated which exhibited satisfactory results, indicating that iQAMS method could be used for quantitative analysis of sucrose and oligosaccharides in P. heterophylla instead of ESM. The iQAMS combined with HPLC-CAD fingerprint could be used to determine the content of each oligosaccharide, and it can be used for quality control of P. heterophylla. • P. heterophylla and its adulterants were firstly rapid identification by HPLC-CAD fingerprint. • A novel method, HPLC-CAD combined with improved QAMS, was developed for P. heterophylla analysis. • Total contents of sucrose and oligosaccharides were quantified by improved QAMS with PHO DP3–1 and PHO DP4. • The developed QAMS can improve the accuracy of HPLC quantification with gradient elution in the absence of reference standards. [ABSTRACT FROM AUTHOR]

A new analytical methodology was proposed to determine fourteen bisphenols in honeys from different botanical origins using ultra-high performance liquid chromatography-tandem mass spectrometry. A fast, efficient, environmentally-friendly and simple sample treatment (recoveries between 81% and 116%; matrix effect <20% for all studied compounds except for bisphenol E, F and S) was proposed, which involved a solvent microextraction with acetone and a small volume/amount of 1-hexanol. Chromatographic analysis (< 15 min) was performed in a Kinetex EVO C 18 column under gradient elution mode. The method was validated in terms of selectivity, limits of detection (0.2–1.5 μg/kg) and quantification (0.5–4.7 μg/kg), linearity, matrix effect, trueness, and precision (relative standard deviation <17%). Finally, thirty honey samples were analyzed, revealing the presence of residues of nine bisphenols in some of them. However, quantification was possible only in two cases for bisphenol A, with a concentration of approximately 13 μg/kg. [Display omitted] • A new method was proposed and validated for determining 14 bisphenols in honeys. • Sample treatment consists of a solvent extraction with acetone and 1-hexanol. • Matrix effect was significant (> 20%) for three bisphenols (E, F and S). • The LOQs were lower than the SMLs established by current legislation. • Residues of nine bisphenols were detected in some of the analyzed honey samples. [ABSTRACT FROM AUTHOR]

Unecritinib (TQ-B3101) is a selective tyrosine kinase receptor inhibitor. In the study, in vitro metabolic experiments revealed that the hydrolysis of TQ-B3101 was mainly catalyzed by carboxylesterase 2 (CES2), followed by CES1. Next, a sensitive and reliable LC-MS/MS method was established for the simultaneous determination of TQ-B3101 and its metabolite crizotinib in rat plasma. To prevent in vitro hydrolysis of TQ-B3101, sodium fluoride, the CESs inhibitor at a concentration of 2 M , was immediately added after whole blood collection. Plasma samples were extracted by acetonitrile-induced protein precipitation method, and chromatographically separated on a Gemini C 18 column (50 mm × 2.0 mm i.d., 5 μm) using gradient elution with a mobile phase of 0.1% formic acid and 5 mmol/L ammonium acetate with 0.1% formic acid. The retention times for TQ-B3101 and crizotinib were 2.61 and 2.38 min, respectively. The analytes were detected with tandem mass spectrometer by positive electrospray ionization, using the ion transitions at m/z 492.3 → 302.3 for TQ-B3101, m/z 450.3 → 260.3 for crizotinib, and m/z 494.0 → 394.3 for imatinib (internal standard). Method validation was conducted in the linear range of 1.00–800 ng/mL for the two analytes. The precision, accuracy and stabilities all met the acceptance criteria. The pharmacokinetic study indicated that TQ-B3101 was rapidly hydrolyzed to crizotinib with the elimination half-life of 1.11 h after a single gavage administration of 27 mg/kg to Sprague-Dawley rats, and the plasma exposure of TQ-B3101 was only 2.98% of that of crizotinib. • TQ-B3101 is an amide prodrug of crizotinib, a selective tyrosine kinase receptor inhibitor. • First LC-MS/MS method for the simultaneous quantification of TQ-B3101 and crizotinib in rat plasma. • The developed method was successfully applied to a pharmacokinetic study. [ABSTRACT FROM AUTHOR]

Arginase is an enzyme responsible for converting arginine, a semi-essential amino acid, to ornithine and urea. Arginine depletion suppresses immunity via multiple mechanisms including inhibition of T-cell and NK cell proliferation and activity. Arginase inhibition is therefore an attractive mechanism to potentially reverse immune suppression and thus has been explored as a therapy for oncology and respiratory indications. Small molecules targeting arginase present significant bioanalytical challenges for in vitro and in vivo characterization as inhibitors of arginase are typically hydrophilic in nature. The resulting low or negative LogD characteristics are incompatible with common analytical methods such as RP-ESI-MS/MS. Accordingly, a sensitive, high-throughput bioanalytical method was developed by incorporating benzoyl chloride derivatization to increase the hydrophobic characteristics of these polar analytes. Samples were separated by reversed phase chromatography on a Waters XBridge BEH C18 3.5 μm, 30 × 3 mm column using gradient elution. The mass spec was operated in positive mode using electrospray ionization. The m/z 434.1→176.1, 439.4→181.2, 334.9→150.0 and 339.9→150.0 for AZD0011, AZD0011 IS, AZD0011-PL and AZD0011-PL IS respectively were used for quantitation. The linear calibration range of the assay was 1.00–10,000 ng/mL with QC values of 5, 50 and 500 ng/mL. The qualified method presented herein exhibits a novel, robust analytical performance and was successfully applied to evaluate the in vivo ADME properties of boronic acid-based arginase inhibitor prodrug AZD0011 and its active payload AZD0011-PL. [Display omitted] • Arginase inhibition as a potential mechanism to reverse immune suppression. • Water loss from parent mass observed when using APCI, but not with ESI. • Prodrug was utilized to increase bioavailability utilizing PEPT1 transporter. • Derivatization with benzoyl chloride to facilitate reversed phase chromatography of polar compounds. • LC-MS/MS method qualification of prodrug and parent compounds. [ABSTRACT FROM AUTHOR]

• 11 free fatty acids were simultaneously determined by LC-MS/MS. • Microvolume serum pretreated by two-step derivatisation strategy. • High throughput analysis of samples can be achieved. • Method was developed and validated with good results. A stable isotope dilution–liquid chromatography–tandem mass spectrometry method based on a derivatisation strategy involving an N,N'-carbonylimidazole solution (CDI) with 4-(dimethylamino)-benzenemethanamine was developed for the determination of 11 free fatty acids (FFAs) in human blood samples. Serum samples were subjected to liquid‒liquid extraction and centrifuged, and the supernatant was collected for a two-step derivatisation reaction with a CDI and 4-(dimethylamino)-aniline acetonitrile solution. The derivatised solution was separated on a ACQUITY UPLC HSS T3 column (2.1 × 50 mm, 1.8 µm) column with a mobile phase consisting of water–acetonitrile in gradient elution and then detected by tandem mass spectrometry using electrospray ionisation (ESI) and multiple reaction monitoring (MRM) in positive ion mode and quantified using the isotope internal standard method. The effects of the derivatisation reaction time, temperature and concentration of derivatisation reagents on the response values of the analytes were investigated. The optimal conditions were as follows: 1.0 mg mL−1 CDI acetonitrile solution at 25 °C for 25 min, followed by a reaction with a 1.0 mg mL−1 4-(dimethylamino)-benzenemethanamine acetonitrile solution at 70 °C for 30 min. Under the optimal conditions, the limits of detection (LODs) of the 11 FFAs were in the range of 3.0–14.0 ng mL−1; the limits of quantification (LOQs) were in the range of 8.0–45.0 ng mL−1; and the mean recoveries ranged from 83.4 to 112.8%, with intraday and interday precisions ranging from 0.7 to 9.1% and 3.7–9.5%, respectively. The experimental method is simple in terms of the pretreatment operation, accurate and reliable, and can be applied to the sensitive determination of FFAs in human blood samples. [ABSTRACT FROM AUTHOR]

A sensitive, reproducible, robust, high-throughput ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method was developed and validated for the simultaneous quantification of fexofenadine and olmesartan in human serum. Samples (50 µL) undergo protein precipitation prior to UPLC-MS/MS analysis. The analytes were separated using an Acquity BEH C18 column (2.1 mm × 50 mm, 1.7 µm) at a flow rate of 0.5 mL/min using a gradient elution with a total run time of 4 min. The analytes were detected in positive ion mode and selected reaction monitoring (SRM) was used for quantitation. The standard curve concentration range was 1.0–500.0 ng/mL for both analytes and each analyte showed excellent linearity with correlation coefficients (R2 > 0.99). The intra- and inter-day accuracy and precision were ±15% for each analyte, and excellent recovery was demonstrated (93–98%) for both analytes. The method is well suited for high-throughput quantitative determination of fexofenadine and olmesartan simultaneously and was successfully applied to an in vivo pharmacokinetic and transporter phenotyping study in humans. • An assay was validated for fexofenadine and olmesartan quantitation in human serum. • Excellent linearity was achieved for both drugs between 1.0 and 500.0 ng/mL. • A simplified sample preparation procedure allowed for high-throughput analysis. • The method was successfully applied to a pharmacokinetic study in humans. [ABSTRACT FROM AUTHOR]

Technical advances in the field of quality analysis allow an increasingly deeper look into the impurity profile of drugs. The ability to detect unexpected impurities in addition to known impurities ensures the supply of high-quality drugs and can prevent recalls due to the detection of harmful unexpected impurities, as has happened recently with the N -nitrosamine and azido impurities in losartan (LOS) drug products. In the present study, the LC-MS/HRMS approach described by Backer et al. was applied to an even more complex system, being the investigation of 35 LOS drug products and combination preparations purchased in 2018 and 2022 in German pharmacies. The film-coated tablets were analysed by means of four LC-MS/HRMS method variants. For the separation a Zorbax RR StableBond C18 column (3.0 ×100 mm, particle size of 3.5 µm, pore size of 80 Å), a gradient elution and for mass spectrometric detection a qTOF mass spectrometer with electrospray ionization in positive and negative mode was used. An information-dependent acquisition method was applied for the acquisition of high-resolution mass spectrometry data. The combination of an untargeted and a targeted screening approach revealed the finding of eight impurities in total. Beside the five LOS related compounds, LOS impurity F, J, K, L, M, and related compound D from amlodipine besilate, LOS azide and an unknown derivative thereof were detected. Identification and structure elucidation, respectively, were successfully performed using in silico fragmentation. Differences in the impurity profiles of drug products from 2018 and 2022 could be observed. This study shows that broad screening approaches like this are applicable to the analysis of drug products and can be an important enhancement of the quality assurance of medicinal products. [Display omitted] • Analysis of losartan finished dosage forms by means of HRMS. • Structural elucidation by means of MS and MS/MS data. • Verification of proposed structural formulae by in silico fragmentation. • Comparison of the impurity profiles of losartan tablets purchased in 2018 and 2022. • Development of a procedure which provides a broad look into the impurity profile of drugs. [ABSTRACT FROM AUTHOR]

Areca nuts have been used as a traditional Chinese medicine (TCM) for thousands of years. Recent studies have shown that it exhibits good pharmacological activity and toxicity. In this study, the pharmacokinetics of five major components of areca nut extract in rats were investigated using a highly sensitive ultra-performance liquid chromatography coupled with triple quadrupole mass spectrometry (UPLC-MS/MS) method. Arecoline, arecaidine, guvacoline, guvacine, and catechin were separated and quantified accurately using gradient elution with mobile phases of (A) water containing 0.1 % formic acid-10 mM ammonium formate, and (B) methanol. The constituents were detected under a timing switch between the positive and negative ion modes using multiple reaction monitoring (MRM). Each calibration curve had a high R2 value of >0.99. The method accuracies ranged −7.09–11.05 % and precision values were less than 14.36 %. The recovery, matrix effect, selectivity, stability, and carry-over of the method were in accordance with the relevant requirements. It was successfully applied for the investigation of the pharmacokinetics of these five constituents after oral administration of areca nut extract. Pharmacokinetic results indirectly indicated a metabolic relationship between the four areca nut alkaloids in rats. For further clarification of its pharmacodynamic basis, this study provided a theoretical reference. • Sensitive detection of five major components in areca nut using UPLC-MS/MS method. • The pharmacokinetics study of five major components of areca nut extract in rats. • The results indicated a metabolic relationship between the four alkaloids in rats. [ABSTRACT FROM AUTHOR]

Niraparib is a potent and orally bioavailable inhibitor of poly (ADP-ribose) polymerase (PARP) with high specificity for isoforms 1 and 2. It has been approved by the U.S. Food and Drug Administration for ovarian cancer maintenance therapy and is currently under development for various cancers, including glioblastoma. To assess central nervous system (CNS) penetration of niraparib in glioblastoma patients, a novel bioanalytical method was developed to measure total and unbound niraparib levels in human brain tumor tissue and cerebrospinal fluid (CSF). The method was validated using plasma as a surrogate matrix over the concentration range of 1–10,000 nM on an LC-MS/MS system. The MS/MS detection was conducted in positive electrospray ionization mode, while chromatography was performed using a Kinetex™ PS C18 column with a total 3.5-minute gradient elution run time. The maximum coefficient of variation for both intra- and inter-day precision was 10.6%, with accuracy ranging from 92.8% – 118.5% across all matrices. Niraparib was stable in human brain homogenate for at least 6 hours at room temperature (RT) and 32 days at −20°C, as well as in stock and working solutions for at least 21 hours (RT) and 278 days (4°C). Equilibrium dialysis experiments revealed the fractions unbound of 0.05 and 0.16 for niraparib in human brain and plasma, respectively. The validated method is currently employed to assess niraparib levels in human glioblastoma tissue, CSF, and plasma in an ongoing trial on newly diagnosed glioblastoma and recurrent IDH1/2(+) ATRX mutant glioma patients (NCT05076513). Initial results of calculated total (K p) and unbound (K p,uu) tumor-to-plasma partition coefficients indicate significant brain penetration ability of niraparib in glioblastoma patients. [Display omitted] • The LC-MS/MS method was validated to measure niraparib levels in human plasma, brain tumor, and CSF. • Unbound fractions of niraparib were established in human plasma, brain, and brain tumor. • The total and unbound levels of niraparib in glioblastoma patients have been evaluated. [ABSTRACT FROM AUTHOR]

• Open circular columns (OCC) and open planar columns (OPC) have the highest quality factor (q max). • q max of OCC and OPC is three times larger than that of a core-shell packed column (CSPC). • Peak capacity (n) of LC analysis in a given time at a given pressure is proportional to q max. • OCC and OPC can generate 3 times larger n than CSPC can at the same pressure in the same time. • The challenges of practical implementation of OCC and OPC considered. The largest peak capacity (n) that LC analysis can generate in isocratic or gradient elution analysis of a given sample in a given time at a given pressure is proportional to the quality factor (q max) of its column structure. In this study, the multi-channel structures with open pseudo-planar channel s (OPPC) and open circular channels (OCC) where compared with PC2 – a typical core-shell column packed with 2 μm particles. These columns have q max of 1.27, 1.17 and 0.41, respectively. The former two q max are the highest among all known column structures – about 3 times higher than q max of PC2. This means that the OPPC and OCC can generate about 3 times higher n compared to what a PC2 can in the same analysis time (t anal) at the same pressure, or they require about 81 times shorter t anal (81 is the 4th power of 3) to generate the same n as a PC2 can at the same pressure. However, while PC2 is a commercially available column, there are substantial challenges in manufacturing the OPPC and OCC that can compete with PC2 in practical applications. In order to be competitive with PC2, the OPPC and OCC should have sub-1μm characteristic dimensions (e.g., the inter-pillar distance, g , in OPPC-based pillar array columns, internal diameters of OCC). Thus, in order to compete with PC2 in one scenario, an OPPC requires g ≤ 0.14 μm. Additionally, to be competitive with PC2, OPPC and OCC should be able to sustain the same high pressure. Highlighting the challenges of their design and manufacturing might help to develop the manufacturable columns substantially superior to the packed ones. [ABSTRACT FROM AUTHOR]

• Multistep pH-peak-focusing LC with a hydrophilic polymer gel column was developed. • Synergism of acac and phen exhibits efficient retention for rare earth metal ions. • Each metal ion is enriched at a pH border formed between two zones of different pH. • Semi-preparative separation of La, Ce, Nd, Eu, Y, Tb, and Yb was achieved. Multistep pH-peak-focusing liquid chromatography with a column packed with a hydrophilic polymer gel (a cross-linked hydroxylated methacrylic polymer gel) was developed for separation of rare earth metal ions. Metal ions in a sample solution introduced to the column are chromatographically extracted into the stationary gel phase at the top of the column equilibrated with a basic solution used as the first mobile phase containing acetylacetone and 1,10-phenanthroline by synergistic extraction effect. After the sample solution is introduced, the mobile phases are delivered into the column by stepwise gradient elution in order of decreasing pH. Each metal ion is concentrated at a pH border formed between the zones of different pH in the column and moves toward the outlet of the column with the pH border. Mutual separation of La(III), Ce(III), Nd(III), Eu(III), Y(III), Tb(III), and Yb(III) was achieved by the present method for an 1-mL sample injection with the column of which the inner volume is 11.8 mL. The multistep pH-peak-focusing liquid chromatography with a hydrophilic polymer gel column developed in this study has great potential as a useful method for the separation of rare earth metal ions on a preparatory scale. [ABSTRACT FROM AUTHOR]

• The simultaneous determination of 14 UV-filters in plasma were developed using LC-MS/MS. • Proteins and phospholipids in plasma are effectively removed. • The method can be applied to monitor human plasma exposure levels of UV-filters. • General population are exposure to UV-filters through multiple sources. Accurate monitoring of UV-filters exposure levels in human plasma is a challenge because of the significant differences in the physicochemical properties of UV-filters, as well as the matrix effect caused by abundant proteins and phospholipids in plasma. Therefore, an effective and rapid method for simultaneous determination of 14 UV-filters in human plasma using protein precipitation-solid phase extraction (SPE) coupled with liquid chromatography tandem mass spectrometry (LC-MS/MS) was developed. Acetonitrile with 0.1 % formic acid and 10 % isopropanol (v/v) were used as mobile phases. A gradient elution on an ACQUITY UPLC BEH-C18 column at 30 °C and 0.3 mL/min flow rate was applied for separation. The electrospray ionization positive or negative modes were selected to determine the corresponding analyte to increase selectivity and sensitivity. Results showed that acetonitrile-tetrahydrofuran (v/v, 8:2) as the extraction solvent can effectively precipitate protein in plasma and improve the solubility of UV-filters. The HybridSPE cartridge improved the removal efficiency of phospholipids, while 1 mL of methanol elution increased the extraction recoveries of targets. Fourteen UV-filters achieved good linearities, low detection limits (0.050 to 0.10 μg/L) and quantification limits (0.10 to 1.0 μg/L). Method accuracy and precision, extraction recoveries, and storage stabilities of all analytes met the criterion of 80–120 %. Moreover, this method was successfully applied for the determination of UV-filters in plasma randomly collected from adults. Nine of 14 UV-filters were determined and their concentrations were distributed widely, suggesting a big variation of individual UV-filters exposure. [ABSTRACT FROM AUTHOR]

An increasing number of drug research institutions consider genotoxic impurity research a core task in drug research and development. Peroxides in drugs may directly or indirectly attack and damage cell DNA, posing a potential carcinogenic risk to the human body. Currently, the literature only studies hydroperoxide impurities, and benzyl peroxide has not been studied yet. In this study, an effective method for ultra-performance liquid chromatography mass spectrometry (UPLC MS/MS) was established and verified to detect and quantify the potential genotoxic impurity (PGI), empagliflozin benzyl peroxide, in metformin–empagliflozin combination formulations, which has not been reported thus far. A Waters ACQUITY UPLC HSS T3 (3.0 ×100 mm, 1.8 µm) column was used to achieve chromatographic separation with gradient elution. The mass spectrometry conditions were optimized using electrospray ionization in the negative mode. Following the International Conference of Harmonization (ICH) guidelines, this methodology can quantify PGIs at 1.35 ng/mL (5.4 ppm) in samples. This validated method exhibited good linearity over a concentration range of 5.4 to 36 ppm, and the accuracy of this method was in the range of 83.2–95.0% for empagliflozin benzyl peroxide. This approach fills the gap in the detection method for benzyl peroxide impurities in metformin hydrochloride and empagliflozin tablets, providing technical support for the quality control of the drug. • A potentially new genotoxic impurity, benzyl peroxide, was identified. • Impurities in metformin–empagliflozin combination formulations were detected. • Hydroperoxide is unstable and produces reactive free radicals that attack DNA. • A method was developed and validated for trace–level quantification of impurities [ABSTRACT FROM AUTHOR]

• Antimicrobial pharmacokinetics is an emerging area of gut microbiome research. • Omadacyline is a tetracycline-class antibiotic with potent activity against Clostridioides difficile and a low propensity to cause C. difficile infection. • This study developed and validated a LC-MS/MS method to quantify omadacycline and its epimerization in stool. • A remarkable epimerization of omadacycline was observed in stool samples. This study developed and validated a new liquid chromatography-tandem mass spectrometry (LC-MS/MS) method to quantify omadacycline and its epimerization in stool to facilitate microbiome studies. Omadacycline was extracted in a methanol-water-ethylenediaminetetraacetic acid (ETDA) solvent containing deuterated omadacycline as internal standard, followed by dilution. In an optimal gradient elution mode, omadacycline and its C4 epimer were separated within 5 min on reversed-phase C18 column. The method showed a broad working range of 0.1–200 ng/ml with a limitation of detection (LOD) of 0.03 ng/ml, little fecal matrix effect, good intra-day and inter-day accuracy (90–101 %), precision (2–15 %), and recovery rate (99–105 %). The method was sufficiently sensitive to quantify omadacycline in human fecal samples (n = 82) collected during a 10-day therapy course and at follow-up (day 13 and day 30) that ranged from 1 to 4785 µg/g. Further analysis revealed that ∼9 % of omadacycline was epimerized in fecal matrix control while, on average, 37.4 % was epimerized in human fecal samples. This study developed and validated a novel, simple, sensitive, and accurate method utilizing LC-MS/MS to quantify omadacycline its epimerization in the human gut. This has important implications for future studies of omadacycline and other tetracycline-class antibiotics as part of gut microbiome studies. [ABSTRACT FROM AUTHOR]

[Display omitted] • A multi-analyte multi-purpose HPLC method was developed for simultaneous analysis of diclofenac sodium, bromfenac sodium, nepafenac and benzalkonium chloride. • Specificity of the method was confirmed by forced degradation study and separation of the drugs from the degradation peaks, related substances and potential impurities. • The developed method allowed separation of up to 10 peaks including active ingredients and impurities in less than 13 min. • The designed method was applied for assay of several ophthalmic preparations. • Greenness and whiteness/sustainability merits were assessed using AGREE and RGB-12 tools. This research presents a validated, multipurpose and sustainable HPLC-DAD method intended for the separation and simultaneous determination of three related non-steroidal ant-inflammatory drugs (NSAIDs): diclofenac sodium, bromfenac sodium and nepafenac in the presence of five of their related compounds and suspected impurities. A Venusil XBP Cyano column with gradient elution of a mobile phase involving methanol, acetonitrile and mixed phosphate and sodium pentane sulfonate buffer (pH 2.5) were employed. DAD was tuned at 210, 233 and 275 nm for measuring peak areas of different analytes. The proposed procedure was successfully validated and utilized in comprehensive stability study of the investigated drugs. The three NSAIDs have been determined within a linearity range of 5–150 µg/mL with excellent analytical performance. The method targeted their analysis in variable dosage forms particularly ophthalmic liquid preparations. This has evolved the need to determine benzalkonium chloride as well which is a common preservative in such dosage forms. It was measured in the range 10–200 µg/mL. The least detectable concentration levels of the analytes were within the range 0.5–2.0 µg/mL. Comparing the designed method to a number of reported ones with respect to greenness and whiteness/sustainability merits using AGREE and RGB-12 paradigms proved it is significantly eco-friendly and represents a green/white option for multi-analyte stability indicating analysis of the above-mentioned drugs. [ABSTRACT FROM AUTHOR]

Red yeast rice (RYR) is a popular food product with significant quality control challenges. This study first established a gradient elution tower plate theory suitable for gradient elution and proposed a dual-label system calibration method to monitor and correct chromatographic systems for changes. Subsequently, high-performance liquid chromatography as the analytical method, and a five-wavelength maximization profile was employed to obtain comprehensive chromatographic information on RYR. A novel multi-marker assay by monolinear method (MAML) was employed for the accurate quantitative determination of quality markers. A differential scanning calorimetry (DSC) quantized fingerprint was established to study complete thermal changes. The comprehensive linear quantitative fingerprint method (CLQFM) was also developed to evaluate fingerprints. Results showed that the CLQFM divides the samples into four quality grades, MAML yielded better results than quantitative analysis of multi-components by a single marker method. Thermal analysis revealed that treatment temperatures higher than 193.7 °C for extended periods should be avoided to maintain sample quality. This study promotes the dual control of the quality and thermal stability of RYR, providing a new direction for food control. • Innovative establishment of HPLC five-wavelengths maximization profilings for red yeast rice. • Analysis of the overall heat behavior in red yeast rice. • The "Multi-markers assay by monolinear method" was developed for red yeast rice quantification. • Established gradient elution tower plate theory and a dual label system calibration method. [ABSTRACT FROM AUTHOR]

[Display omitted] • Optimization of the yield of tocol esterification reaction. • Separation of β- and γ-forms of tocol esters by C18-UFLC. • Direct C18-UFLC-DAD-FLD analyses of tocols in oils. • UV absorption spectra of esterified tocols. • C18-UFLC analyses of tocols in saponified milk and animal samples. The improved pre-column methods followed by gradient elution C18-chromatography (C18-UFLC) with photodiode (DAD) and fluorescence (FLD) detection for analysis of tocotrienols (T3s), tocopherols (Ts), α-tocopheryl acetate and cholesterol in plant, algae and fish oils, milk and animal tissues have been described. C18-chromatography without saponification permitted quantification of T3s and Ts in oils. Quantification of tocols in milk involved saponification followed by C18-chromatography. β-tocol and γ-tocol were unseparated using C18-chromatography. Esterification of hydroxyl group of tocols with trifluoroacetic anhydride allows their satisfactory separation. The combination of esterification of tocols, C18-chromatography and DAD monitoring at 278 and 205 nm provide the suitable analytical tool for quantification of β- and γ-forms of tocols in biological samples. Our original C18-chromatographic methods are satisfactory precise, accurate, repeatable and offer low values of limit of detection (<10 ng/mL) and limit of quantification (<27 ng/mL) for assayed tocols and cholesterol. [ABSTRACT FROM AUTHOR]

• Chromatographic properties of phosphorylated peptides have been investigated using extensive proteomics-derived datasets. • Retention shifts induced by phosphorylation under reversed-phase separation conditions increase in the order HFBA < TFA < Formic acid < Acetic acid. • Retention shifts induced by phosphorylation under reversed-phase separation conditions increase in the order Tyr < Thr < Ser. • Composition and sequence-dependent factors determining retention shifts have been established. The development of a peptide retention prediction model for reversed-phase chromatography applications in proteomics is reported for peptides carrying phosphorylated Ser, Thr and Tyr-residues. The major retention features have been assessed using a collection of over 10,000 phosphorylated/non-phosphorylated peptide pairs identified in a series 1D and 2D LC-MS/MS acquisitions using formic acid as ion pairing modifier. Single modification event on average results in increased peptide retention for phosphorylation of Ser (+ 1.46), Thr (+1.33), Tyr (+0.93% acetonitrile, ACN) on gradient elution scale for Luna C18(2) stationary phase. We established several composition and sequence specific features, which drive deviations from these average values. Thus, single phosphorylation of serine results in retention shifts ranging from -2.4 to 5.5% ACN depending on position of the residue, nature of nearest neighbour residues, peptide length, hydrophobicity and pI value, and its propensity to form amphipathic helical structures. We established that the altered ion-pairing environment upon phosphorylation is detrimental for this variability. Hydrophobicity of ion-pairing modifier directly informs the magnitude of expected shifts: (most hydrophilic) 0.5 % acetic acid (larger positive shift upon phosphorylation) > 0.1 % formic acid (positive) > 0.1 % trifluoroacetic (negative) > 0.1 % heptafluorobutyric acid (larger negative shift). The effect of phosphorylation has been also evaluated for several separation conditions used in the first dimension of 2D LC applications: high pH reversed-phase (RP), hydrophilic interaction liquid chromatography (HILIC), strong cation- and strong anion exchange separations. [ABSTRACT FROM AUTHOR]

• Multimodal chromatography for standard and multispecific antibody formats. • Mechanistic chromatography model calibrated for 59 full-length IgG derivatives. • Thermodynamic parameters predicted from antibody-specific descriptors. • Multiscale models validated at pH 5.0 to 7.0 for a priori process development. Multimodal chromatography has emerged as a powerful method for the purification of therapeutic antibodies. However, process development of this separation technique remains challenging because of an intricate and molecule-specific interaction towards multimodal ligands, leading to time-consuming and costly experimental optimization. This study presents a multiscale modeling approach to predict the multimodal chromatographic behavior of therapeutic antibodies based on their sequence information. Linear gradient elution (LGE) experiments were performed on an anionic multimodal resin for 59 full-length antibodies, including five different antibody formats at pH 5.0, 6.0, and 7.0 that were used for parameter determination of a linear adsorption model at low loading density conditions. Quantitative structure-property relationship (QSPR) modeling was utilized to correlate the adsorption parameters with up to 1374 global and local physicochemical descriptors calculated from antibody homology models. The final QSPR models employed less than eight descriptors per model and demonstrated high training accuracy (R² > 0.93) and reasonable test set prediction accuracy (Q² > 0.83) for the adsorption parameters. Model evaluation revealed the significance of electrostatic interaction and hydrophobicity in determining the chromatographic behavior of antibodies, as well as the importance of the HFR3 region in antibody binding to the multimodal resin. Chromatographic simulations using the predicted adsorption parameters showed good agreement with the experimental data for the vast majority of antibodies not employed during the model training. The results of this study demonstrate the potential of sequence-based prediction for determining chromatographic behavior in therapeutic antibody purification. This approach leads to more efficient and cost-effective process development, providing a valuable tool for the biopharmaceutical industry. [ABSTRACT FROM AUTHOR]

A new reverse osmosis (RO) permeate remineralization process combining ion exchange resin and bipolar membrane electrodialysis (BMED) was developed. Its feasibility for hardness ions recovery and RO permeate remineralization was investigated. The effect of several operation conditions on the efficiency of the combined remineralization process was studied. Highly efficient cation exchange resin loading was achieved at a low flow rate and low feed solution concentration. The recovered calcium purity and yield considerably improved under gradient elution methods in comparison with commonly applied conventional isocratic elution methods using the same eluent quantity. The purity of the produced acid and base using BMED dropped noticeably with increasing feed NaCl concentration, presumably related to decreased permselectivity of the ion-exchange membranes. The drop in the purity of the calcium recovered when eluting the cation exchange resin with BMED-produced HCl in comparison with commercially available acid at 50 % yield was shown not to affect the remineralization process, where a dilution factor could be applied. This study confirmed the technical feasibility of the developed process for RO permeate remineralization. However, its application can be limited by the water source characteristics, the energy-intensive bipolar membrane process, and applied operational conditions, where more investigation is still needed. [Display omitted] • A new remineralization process for RO permeate is proposed. • The process is based on a combined ion exchange-bipolar membrane hybrid process. • Cation exchange is used for hardness removal and recovery. • Bipolar membrane electrodialysis is used for HCl and NaOH production from NaCl. • Total treatment cost is comparable to conventional remineralization processes. [ABSTRACT FROM AUTHOR]

DO-2 is a highly selective MNNG HOS transforming (MET) inhibitor. This deuterated drug is thought to diminish the formation of the Aldehyde Oxidase 1 inactive metabolite M3. For various reasons, quantification of DO-2 and its metabolites M3 and DO-5 is highly relevant. In this study, we present an ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) method to quantify DO-2, M3 and DO-5. Rolipram served as the internal standard. Aliquots of 25 µL were mixed with 100 µL internal standard consisting of 10 ng/mL rolipram in acetonitrile. Separation of the analytes was achieved on an Acquity UPLC ® HSS T3 column, utilizing gradient elution with water/formic acid and acetonitrile/formic acid at a flow-rate of 0.400 mL/min. Calibration curves were linear in the range of 1.00 – 1000 ng/mL for DO-2 and DO-5, and 2.00 – 2000 ng/mL for M3 in human plasma. The within-run and between-run precisions of DO-2, DO-5 and M3, also at the level of the LLQ, were within 12.1%, while the accuracy ranged from 89.5 to 108.7%. All values for accuracy, within-run and between-run precisions met the criteria set by the Food and Drug Administration. The method was effectively employed in the analysis of samples obtained from a clinical trial. [Display omitted] • We describe the first UPLC-MS/MS method for the analysis of DO-2 and its metabolites DO-5 and M3 in human plasma. • The assay met all of the current requirements of bioanalytical method validation. • Clinical applicability of the assay was demonstrated for pharmacokinetic analysis in clinical pharmacokinetic studies. [ABSTRACT FROM AUTHOR]

Recalls of medicinal products can cause supply bottlenecks. This is often due to the findings of unexpected impurities that pose a health risk to patients. A recent example is losartan potassium which was contaminated with azido-impurities. The choice of the analytical method determines which substances can be detected and thus controlled. In this study a combination of an untargeted screening approach for impurities and a targeted evaluation of high-resolution mass spectrometry data was applied to search for impurities not described so far, leaving out a precise quantification. Six losartan potassium samples were studied regarding known and unknown impurities and hence highlight the applicability and capability of the approach. For separation a Zorbax RR StableBond C18 column (3.0 ×100 mm, particle size of 3.5 µm, pore size of 80 Å), a gradient elution and an electrospray ionization in positive and negative mode for mass spectrometric detection was used. An information-dependent acquisition method was applied for the measurement of losartan potassium samples. The untargeted data evaluation using general unknown comparative screening revealed the presence of N -methyl-2-pyrrolidone (NMP) and another impurity from synthesis. The identity of NMP was corroborated by a spiking experiment and the amount was estimated by means of standard addition. A targeted data evaluation by generating extracted ion chromatograms resulted in finding of four additional impurities. Combined approaches like this are needed to detect and respond to changes in the quality of drugs precociously. [Display omitted] • Impurity profiling of losartan potassium with targeted and untargeted approaches. • Structural elucidation by means of high resolution mass spectrometry data. • Detection and identification of impurities not structurally related to losartan. • Procedure that can help to avoid expensive drug recalls. [ABSTRACT FROM AUTHOR]

• Develop and validate an LC-MS/MS method for the quantification of six small molecule Anti-SARS-CoV-2 drugs in plasma. • The devised methodology was effectively utilized in a pharmacokinetic study following the oral administration of six small molecule Anti-SARS-CoV-2 drugs in rats. • Presents a significant tool for preclinical and clinical investigations of six small molecule Anti-SARS-CoV-2 drugs, generating interest in further research on anti-Covid19 drugs. Antiviral treatment for COVID-19 is considered an effective tool in reducing the rate of severe cases and deaths. As of June 2023, a total of six small molecule antiviral drugs have been conditionally approved for marketing by the National Medical Products Administration (NMPA) within China. In this study, a method of HPLC-MS/MS was established and validated for the determination of six small molecule antiviral drugs in plasma using Lamivudine as an internal standard. The chromatographic separation was performed using gradient elution with an ACE 3 C 18 -PFP column (3.0 mm × 150 mm, 3 μm), and the mobile phase consisted of deionized water and acetonitrile/water (90:10, v/v), both with 10 mmol/L of ammonium acetate and 0.1 % ammonium hydroxide added. Quantitative analysis of the six small molecule drugs was carried out through selective reaction monitoring based on the positive ion spray ionization mode. The method exhibited excellent precision, accuracy, recovery, and linearity, and it was used to determine the pharmacokinetic characteristics in rats. Our work not only established a bioanalytical method for six small molecule antiviral drugs but also provided scientific references for clinical pharmacokinetic studies. [ABSTRACT FROM AUTHOR]

• Comprehensive 2D RPCCC × RPLC chromatographic analysis of Rheum palmatum L. • 2D bioassay profilings were combined with 2D chromatogram for 2D bioscreening. • Separation and characterization of 11 constituents from Rheum palmatum L. • Two components were identified as natural α -glucosidase inhibitors for the first time. In the present work, comprehensive two-dimensional reversed-phase countercurrent chromatography × reversed-phase liquid chromatography combined (2D RPCCC × RPLC) with 2D microfraction bioactive evaluation was employed to screen and isolate α -glucosidase inhibitors from Rheum palmatum L. Countercurrent chromatography was employed to improve 2D analysis and preparative separation. A selected biphasic solvent system composed of petroleum ether/ethyl acetate/methanol/water with gradient elution mode was used for the first dimension RPCCC separation (1D RPCCC). Solid-phase extraction was applied to eliminate interfering polar compounds before the second dimension analysis (2D RPLC). 76 components were shown in 2D contour plot in UV 280 nm. 11 Candidates were separated by a scaled-up CCC and identified by 1H NMR and 13C NMR, including anthraquinones, flavonoids, stilbenes, phenols, and glucoside derivatives. In addition, it was found that two components, resveratrol-4′- O -(6″-galloyl)glucoside (36) and lyciumaside (43) were identified as natural α -glucosidase inhibitors in Rheum palmatum L. for the first time. [ABSTRACT FROM AUTHOR]

[Display omitted] • HF-LPME and nanoLC-HRMS provide high clean-up efficiency and detectability. • Lab-made columns minimize dead-volume and post-separation dilution. • The applicable concentration interval covers the therapeutic and toxic range. • This method can be applied for therapeutic drug monitoring and forensic purposes. Therapeutic drug monitoring (TDM) is a personalized care tool based on the determination of a target drug concentration in human serum. An antidepressant drug of interest for such investigations is fluoxetine (FXT), due to a severe impact of genetic polymorphisms on its metabolism. A bioanalytical method employed for TDM purposes must exhibit satisfactory selectivity and detectability, which becomes more difficult due to highly complex biological matrices. In this study, a highly selective bioanalytical method for the determination of FXT in human serum is proposed, which provides excellent clean-up efficiency based on a low cost hollow fiber liquid-phase microextraction (HF-LPME) sample preparation step and nano-liquid chromatography coupled to high-resolution mass spectrometry (nano-LC-HRMS). HF-LPME was performed using a two-phase "U" configuration, with 6 cm fiber, 20 µL of 1-octanol acting as supported liquid membrane, and ammonium hydroxide (pH 10) as the donor phase with NaCl (10 % m/v) and methanol (5 % v/v) as additives, requiring only 250 µL of the sample. The procedure was conducted for 30 min under a 750 rpm stirring rate. Gradient elution was carried out employing an acetonitrile–water as mobile phase, the composition of 30:70 to 100:00 (v/v) for 15 min, using formic acid 0.1 % (v/v) as an additive. MS1 was acquired in an Orbitrap mass analyzer, while MS2 was acquired in a linear trap quadrupole. Satisfactory linearity (Pearson's r = 0.99709) was obtained for a concentration range of 0.02 to 2.5 µg mL−1, which is compatible with the therapeutic and toxic range for FXT. The developed method presents adequate precision (1.61 to 7.45 %) and accuracy (95 to 114 %) and allows the dilution of high concentration samples in a 1:4 ratio (v/v), enabling its application for forensic serum samples. To our knowledge, this is the first study reporting a method based on HF-LPME and nano-LC-HRMS with any analytical purpose, especially with a TDM focus. [ABSTRACT FROM AUTHOR]

• A LC-MS/MS method for simultaneous quantification of insulin and liraglutide. • Method was developed and validated following FDA and EMA guidelines. • The method was applied to pharmacokinetics and biodistribution of drugs in rats. • Drugs were quantified in plasma, brain, lung, spleen, liver and kidneys. We present an ultra-performance liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for simultaneous detection of insulin degludec (I-Deg) and liraglutide (LIRA) in rat plasma and tissues, characterized by its sensitivity and selectivity. Chromatographic separation was achieved using an Acquity UPLC BEH C18 column, leveraging a mobile phase of acetonitrile and water (both with 0.1 % formic acid) under gradient elution over a run time of 7.5 min. The mass spectrometer operated in positive electrospray ionization multiple reaction monitoring (MRM) mode, tracking transitions of m / z 1221.6 → 641.6 for I-Deg, m / z 938.7 → 1064.1 for LIRA, and m / z 1184.7 → 454.4 for the internal standard. Validation ranged from 5 to 100 ng/mL, exhibiting robust linearity (r2 > 0.99) and limits of detection (LOD) of 1.63–2.02 ng/mL for I-Deg and 0.96–1.62 ng/mL for LIRA. Limits of quantification (LOQ) were 2.38–4.76 ng/mL for I-Deg and 3.22–4.40 ng/mL for LIRA. Notably, no significant matrix effects were detected. Stability was confirmed under various conditions, and precision metrics (intraday RSD 1.68–8.05 % for I-Deg and 1.11–7.69 % for LIRA; interday RSD 1.39–8.61 % for I-Deg and 1.06–8.83 % for LIRA) alongside accuracy (90.5–114.9 % for I-Deg and 92.7–113.7 % for LIRA) were within acceptable ranges. The method was successfully applied to pharmacokinetic and biodistribution studies following simultaneous subcutaneous administration of LIRA and I-Deg in rats. [ABSTRACT FROM AUTHOR]