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In this paper a dispersive magnetic-solid phase extraction (MSPE) using a graphene nanocomposite (rG/Fe 3 O 4 ) followed by ultra high performance liquid chromatography with photodiode array detection has been developed for the simultaneous analysis of new class of oral anticoagulants (NOAs) in human plasma. The performance of the nanocomposite graphene@Fe 3 O 4 on the magnetic solid phase extraction of apixaban, rivaroxaban and dabigatran has been optimized using a Box-Behnken design of experiment. The amount of graphene nanocomposite, the sample pH and the adsorption time were the investigated parameters as a function of the extraction recovery. The analytical method was fully validated based on linearity, limit of detection (LOD), limit of detection (LOQ), inter- and intra-day precision and trueness, and extraction yield. Under optimal condition, excellent linearity (R 2 > 0.9987) over the range (0.001-5.0 μg/mL), limit of detection (0.003 μg/mL), precision (0.81-8.97% RSD) and trueness (-5 to 9 % BIAS%) were observed for the target drugs. The average extraction recovery under optimal from plasma samples ranged between 96.6-98.6% for apixaban, rivaroxaban and dabigatran and the internal standard. The proposed method was developed, validated and successfully applied to the measurement of these NOAs in patients. The new approach offers an attractive alternative for the simultaneous analysis of the selected NOAs from plasma samples, providing several advantages including fewer sample preparation steps, ease of performance, and higher recoveries compared to traditional methodologies., (Copyright © 2019 Elsevier B.V. All rights reserved.)

A novel, rapid, simple graphene/Fe 3 O 4 based dispersive magnetic solid phase extraction was developed for the simultaneous separation/preconcentration and determination of non steroidal anti-inflammatory drugs with ultra high performance liquid chromatography coupled with photodiode array detection. Several parameters influencing the extraction efficiency of the investigated analytes such as the extraction time, the amount of graphene/Fe 3 O 4 , the sample pH, the ionic strength and the elution solvent were evaluated and optimized. Under optimal conditions, the linearity was in the range of 0.002-25 μg/mL for furprofen, diclofenac and ketoprofen, 0.003-25 for flurbiprofen, naproxen and fenbufen, 0.004-25 for indoprofen with a good coefficient of determination (R 2 > 0.9991) for each analyte. The inter-and- intra day accuracy (BIAS%) for human plasma and urine ranged between -7.15% to 6.20% and -5.17% to 4.87%, respectively.The precision (RSD%) in human plasma and urine was less than 8.67% and 8.92%, respectively. The proposed method was applied to the determination of NSAIDs in human plasma and urine., (Copyright © 2018. Published by Elsevier B.V.)

An ultra high-performance liquid chromatographic (UHPLC) method with PDA detection was developed and validated for the simultaneous quantification of metronidazole, meropenem, ciprofloxacin, linezolid and piperacillin in human plasma and applied to patients suffering from hospital acquired pneumonia (HAP). The method uses an air assisted dispersive liquid-liquid microextraction for sample preparation. All parameters in the extraction step, including selection of extractant, amount of extractant, ionic strength, pH, and extraction cycles, were investigated and optimized. Chromatography was carried out using a Poroshell 120 SB C 18 (50 × 2.1 mm I.D. 2.6 μm particle size) column and a gradient mobile phase consisting of ammonium acetate buffer (10 mM, pH 4.0) (eluent A); and a mixture of acetonitrile-methanol in a ratio (80/20)(eluent B). Ulifloxacin was used as internal standard. The method demonstrated good linearity with correlation coefficients, r 2  > 0.9995 for the drugs, as well as high precision (RSD% ≤ 9.87%), accuracy ranged from -8.14% to +8.98. The enrichment factor (EF) obtained ranged within 87 and 121. During the validation, the concentrations of the analytes were found to be stable after 3 freeze-thaw cycles and for at least 24 h after extraction. Subsequently, this method was used to quantify the drugs in patients with HAP in order to establish if the dosage regimen given was sufficient to eradicate the infection at the target site., (Copyright © 2017. Published by Elsevier B.V.)

An ultra high-performance liquid chromatographic (UHPLC) method with PDA detection was developed and validated for the simultaneous quantification of meropenem, linezolid, and levofloxacin in human plasma and applied in human plasma of critical care patients. A semi-automated microextraction by packed sorbent (MEPS) for sample preparation was used. All parameters in the extraction step (pH, sample volume, sample dilution and number of aspiration - ejection cycles) and in the desorption step (percentage of acetonitrile in the solvent of elution and number of aspirations of elution solvent through the device) were statistically significant when the recovery was used as response. The method showed good linearity with correlation coefficients, r 2 >0.9991 for the three drugs, as well as high precision (RSD%<10.83% in each case). Accuracy ranged from -7.8% to +6.7%. The limit of quantification of the three drugs was established at 0.01μg/mL for linezolid and levofloxacin and 0.02μg/mL for meropenem. Linezolid, meropenem, levofloxacin and the internal standard were extracted from human plasma with a mean recovery ranged from 92.4% to 97.4%. During validation, the concentration of meropenem, linezolid and levofloxacin was found to be stable after 3 freeze-thaw cycles and for at least 24h after extraction. This method will be subsequently used to quantify the drugs in patients to establish if the dosage regimen given is sufficient to eradicate the infection at the target site., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Oxyprenylated natural products were shown to exert in vitro and in vivo remarkable anti-cancer and anti-inflammatory effects. This paper describes a rapid, selective, and sensitive HPLC method with fluorescence detection for determination of 4'-geranyloxyferulic acid (GOFA) and its conjugate with l-nitroarginine methyl ester (GOFA-L-NAME) in mononuclear cells. Analytes were extracted from cells using methanol and eluted on a GraceSmart RP 18 analytical column (250×4.6mm i.d., 5μm particle size) kept at 25°C. A mixture of formic acid 1% in water (A) and methanol (B) were used as mobile phase, at a flow-rate of 1.2mL/min in gradient elution. A fluorescence detector (excitation/emission wavelength of 319/398nm for GOFA and GOFA-L-NAME), was used for the two analytes. Calibration curves of GOFA and GOFA-L-NAME were linear over the concentration range of 1.0-50μg/mL, with correlation coefficients (r 2 )≥0.9995. Intra- and inter-assay precision do not exceed 6.8%. The accuracy was from 94% to 105% for quality control samples (2.0, 25.0 and 40μg/mL). The mean (RSD%) extraction recoveries (n=5) for GOFA and GOFA-L-NAME from spiked cells at 2.0, 25.0 and 40.0μg/mL were 92.4±1.5%, 94.7±0.9% and 93.8±1.1%, for GOFA and 95.3±1.2%, 94.8±1.0% and 93.9±1.3%, for GOFA-L-NAME. The limits of detection and quantification were 0.3μg/mL and 1.0μg/mL for GOFA and GOFA-L-NAME. This method was successfully applied to measure GOFA and GOFA-L-NAME concentrations in a mononuclear cells., (Copyright © 2016 Elsevier B.V. All rights reserved.)

A novel sensitive analytical method based on the use of a semi-automatic microextraction by packed sorbents (MEPS) techniques combined with ultra high-performance liquid chromatography (UHPLC) with PDA detection has been developed and validate for the analysis of ulifloxacin, the active metabolite of prulifloxacin using danofloxacin as internal standard in human plasma and urine. Different experimental parameters were optimized and validated according to international guidelines. Complete separation of the analytes was achieved with a Waters BEH C18 (50×2.1mm I.D., 1.7μm particle size) analytical column, a mixture of 10mM ammonium acetate (pH 3.0) (A) with and acetonitrile (B) both containing 1% triethylamine were used as mobile phase, at a flow rate of 0.6mL/min in gradient elution, and detection wavelength of 272nm. This method is linear in concentration range of 0.02-10.0μg/mL for plasma and urine, respectively. The limit of quantitation was 20ng/mL for the two fluids. The recoveries of the method were 95% for ulifloxacin in human plasma and urine and 95.5% for the internal standard. Intra- and inter- assay precision and accuracy for ulifloxacin were lower than 10% at all tested concentrations. The proposed method was successfully applied to measure plasma and urine concentrations of ulifloxacin in patients suffering from Peripheral Arterial Disease and for pharmacokinetics study., (Copyright © 2016 Elsevier B.V. All rights reserved.)

A procedure based on microextraction by packed sorbent (MEPS) followed by ultra-high performance liquid chromatography (UHPLC) with photodiode array (PDA) detection has been developed for the analysis of seven selected non steroidal anti-inflammatory drugs (NSAIDs) in human dialysates. The influence on MEPS efficiency of pH of the sample, pH of the washing solvent and methanol content in the hydro-alcoholic elution mixture has been investigated by response surface methodology based on a Box-Behnken design of experiments. Among the above factors, pH of sample is the variable that mostly influences MEPS recovery. UHPLC separation of the NSAIDs was completed within less than 4min under isocratic elution conditions on a Fortis SpeedCore C18 column (150×4.6mm I.D., 2.6μm) using acetonitrile-phosphate buffer as the mobile phase. Calibration curves of the NSAIDs were linear over the concentration range 0.025-15μg/mL, with correlation coefficients≥0.998. Intra- and inter-assay relative standard deviations were <8% and recovery values ranged from 94% to 100% for the quality control samples. The results reveal that the developed MEPS/PDA-UHPLC method exhibits a good accuracy and precision and is well suited for the rapid analysis of human dialysate from patients treated with the selected NSAIDs., (Copyright © 2016 Elsevier B.V. All rights reserved.)

A procedure based on solid-phase extraction (SPE) followed by high performance liquid chromatography (HPLC) with PDA detection has been developed for the analysis of multiple drugs in rat plasma. The analytes evaluated were ulifloxacin, fenbufen and felbinac. Eight different solid phase extraction cartridges were tested to evaluate their applicability for the isolation of drugs from rat plasma. Comparison were recovery of different drugs and reproducibility. The samples were analyzed by HPLC using a Kinetex C18 EVO column and acetonitrile-10mM ammonium acetate-methanol as the mobile phase under gradient elution conditions. SPE combined with HPLC-PDA allowed the determination of drugs over a linear range of 0.05-15 μg/mL for ulifloxacin while 0.5-50 μg/mL for felbinac and fenbufen, with limit of detection at 0.05 for ulifloxacin and 0.5 for felbinac and fenbufen. Bond Elut Plexa sorbent was found to provide the most effective clean-up, removing the greatest amount of interfering substance and simultaneously ensuring analyte recoveries higher than 93.54% with relative standard deviation (RSD) <10%. The method was applied with good accuracy and precision in the determination of ulifloxacin, fenbufen and felbinac in rat plasma obtained from rats treated with selected drugs. This method permits its application to pharmacokinetic and pharmacodynamic studies of these analytes and will facilitate detailed investigations on the interactions between new fluoroquinolones and fenbufen., (Copyright © 2016. Published by Elsevier B.V.)

A novel HPLC method for the simultaneous determination of Prulifloxacin, Ulifloxacin, its process impurities in a tablets formulation and Enrofloxacin, used as Internal Standard, is developed. The separation was successfully carried out with a new stationary phase, HILIC, under isocratic elution mode using ammonium acetate buffer (5 mM, pH 5.8) and acetonitrile (12:88, v/v) at a flow rate of 1.0 mL/min. Column was thermostated at 25 °C (±1 °C) and 20 μL were injected for the analysis. Calibration curves were linear in the investigated range with correlation coefficient better than 0.9880, while the limit of quantifications ranged from 0.25 to 5 μg/mL, depending from the analyte. The within and between batch precision (RSD%) values ranged from 0.11% to 13.9% while within and between batch trueness (bias%) values ranged from 14.0% to -11.3%. This method for the direct determination and quantification of process impurities in pharmaceutical formulations is suitable for routine analyses in quality control laboratories and was applied to evaluate for the first time, the presence and the quantities of cited analytes in commercially available formulation., (Copyright © 2013 Elsevier B.V. All rights reserved.)

Oxyprenylated natural products (isopentenyloxy-, geranyloxy- and the less spread farnesyloxy-compounds and their biosynthetic derivatives) represent a family of secondary metabolites that have been consider for years merely as biosynthetic intermediates of the most abundant C-prenylated derivatives. Many of the isolated oxyprenylated natural products were shown to exert in vitro and in vivo remarkable anti-cancer and anti-inflammatory effects. 4'-Geranyloxyferulic acid [3-(4'-geranyloxy-3'-methoxyphenyl)-2-trans-propenoic] has been discovered as a valuable chemopreventive agent of several types of cancer. After development of a high yield and "eco-friendly" synthetic scheme of this secondary metabolite, starting from cheap and non-toxic reagents and substrates, we developed a new HPLC-DAD method for its quantification in grapefruit skin extract. A preliminary study on C18 column showed the separation between GOFA and boropinic acid (having the same core but with an isopentenyloxy side chain), used as internal standard. The tested column were thermostated at 28+/-1 degrees C and the separation was achieved in gradient condition at a flow rate of 1 mL/min with a starting mobile phase of H(2)O:methanol (40:60, v/v, 1% formic acid). The limit of detection (LOD, S/N=3) was 0.5 microg/mL and the limit of quantification (LOQ, S/N=10) was 1 microg/mL. Matrix-matched standard curves showed linearity up to 75 microg/mL. In the analytical range the precision (RSD%) values were

The optimization of the HPLC procedures and the investigation of the predictive models are generally seen as distinct tasks although they could be both approached by very similar chemometric methods. In this work we used chemometric approaches to both optimize the separation of a non-steroidal anti-inflammatory drugs (NSAIDs) set by isocratic reversed-phase HPLC and start-up the development of retention predictive models. The screening of responsive variables and the search for an optimal experimental domain provided also an insight into the structure-chromatographic response relationships for the considered compounds which were particularly helpful to derive new retention parameters.

Ketoprofen lysine salt (Artrosilene) Fiale) is a non-steroidal anti-inflammatory agent frequently administered by intravenous infusion in association regimen with other drugs, such as steroidal anti-inflammatory, anti-hemorrhagic, anti-spastic, anti-ulcer, and antibacterial drugs. The aim of this study was to investigate the physicochemical compatibility between ketoprofen lysine salt (Artrosilene) Fiale) and other injectable drugs frequently used in association. Physicochemical properties of ketoprofen lysine salt mixtures with different drugs, including colour, clarity, pH and drug content were observed or measured before and after (up to 5 h) mixing at room temperature and under light protection. Results show that the association of Artrosilene Fiale with different drugs does not cause, up to 5 h from mixing, any significant variation in the physicochemical parameters mentioned above. In conclusion, the results obtained demonstrated the physicochemical compatibility of ketoprofen lysine salt (Artrosilene) Fiale) with several drugs.

Capillary Electrophoresis (CE) and Capillary Electrochromatography (CEC) have been used to determine losartan and hydrochlorothiazide. The CE separation was carried out in an uncoated capillary filled with a 100 mM sodium borate pH 9 solution containing trimethyl-beta-cyclodextrins. CEC was performed using a capillary packed with a RP-18 stationary phase. The mobile phase was a mixture of 50 mM ammonium acetate pH 7, water, acetonitrile (1/1.5/7.5). By CE and CEC suitable methods to determine simultaneously losartan and hydrochlorothiazide in working standard mixture or pharmaceutical form were obtained. The proposed methods are very simple and both gave accurate and precise results.

A method for the simultaneous determination of losartan potassium and hydrochlorothiazide in tablets is described. The procedure, based on the use of reversed-phase high-performance liquid chromatography, is linear in the concentration range 3.0-7.0 microg ml(-1) for losartan and 0.5-2.0 microg ml(-1) for hydrochlorothiazide, is simple and rapid and allows accurate and precise results. The limit of detection was 0.08 microg ml(-1) for losartan and 0.05 microg ml(-1) for hydrochlorothiazide.

A high-performance liquid chromatographic method for the simultaneous determination of 5-aminosalicylic acid (5-ASA), acetyl-5-aminosalicylic acid (Ac-5-ASA) and 2,5-dihydroxybenzoic acid (5-HSA) in human endoscopic intestinal biopsy with electrochemical detection has been developed and validated. A liquid-liquid extraction procedure was used to isolate these drugs from the biological material prior to analysis. The compounds were separated on an Erbasil S reversed-phase column using methanol-critic acid-sodium hydrogenphosphate-heptane-sulfonic acid-disodium ethylenediaminetetraacetate (pH 3) as mobile phase. The method was linear from 1.0 to 300 ng ml-1 for 5-ASA, from 10 to 1000 ng ml-1 for Ac-5ASA and from 0.1 to 10 ng m-1 for 5-HSA. The limit of detection for 5-ASA and for Ac-5-ASA was 1 ng ml-1 and that for 5-HSA was 0.1 ng ml-1. This procedure is suitable for pharmacological and clinical studies of 5-ASA.

A high-performance liquid chromatographic method for the determination of lomefloxacin in human plasma has been developed and validated. A solid-phase extraction procedure was used to isolate lomefloxacin from the biological matrix prior to the quantitative analysis. The compound was separated on a Vydac anion-exchange column using acetonitrile-phosphate buffer (pH 7.0) as the mobile phase and quantified by measuring its UV absorbance at 280 nm. The lower limit of detection for the analyte was 0.05 micrograms ml-1. Enoxacin was used as the internal standard. The calibration graph of the method was linear from 0.1 to 10 micrograms ml-1 of lomefloxacin in human plasma. This procedure is suitable for pharmacological and pharmacokinetic studies of lomefloxacin.

Simvastatin (SV), an analogue of lovastatin, is the lactone form of 1',2',6',7',8',8a'-hexahydro-3,5-dihydroxy-2',6'-dimethyl-8'(2'',2''-di met hyl-1''-oxobutoxy)-1'-naphthalene-heptanoic acid (SVA) which lowers plasma cholesterol by inhibiting 3-hydroxy-3-methylglutaryl-CoA reductase. A fast, simple and accurate method for determining SV and SVA concentrations in human plasma has been developed and validated for use in the analysis of plasma samples from patients and healthy volunteers. This method involves an extraction procedure using a mixture of acetonitrile-water and reversed-phase high-performance liquid chromatography with UV detection. The procedure was linear from 20 to 1000 ng ml-1 for SV and from 25 to 1000 ng ml-1 for SVA, respectively. The method was accurate with relative errors of 5.0, 2.1 and 3.2% for human plasma controls containing 50, 250 and 500 ng ml-1 of SV, respectively. The corresponding precision was 2.3, 1.8 and 1.0% (RSD%). Similarly, relative standard deviations less than 2.3% and relative errors of less than 5.2% were obtained from human plasma controls containing SVA at identical concentrations. The method is suitable for pharmacology and pharmacokinetic studies of simvastatin.

A simple and reliable HPLC method is described for the new beta-lactam antibiotic imipenem; suitable extraction procedures for the drug in human plasma, urine and prostatic tissue are described. The figures of merit for the assays are reported and examples given of their application.