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We present the inaugural synthesis of a chiral teropyrene achieved through a four‐fold alkyne benzannulation catalyzed by InCl3, resulting in good yields. The product underwent thorough characterization using FT‐Raman and FT‐IR spectroscopies, demonstrating a close agreement with calculated spectra. X‐ray crystallographic analysis unveiled a notable twist in the molecule's backbone, with an end‐to‐end twist angle of 51°, consistent with computational predictions. Experimentally determined enantiomeric inversion barriers revealed a significant energy barrier of 23 kcal/mol, facilitating the isolation of enantiomers for analysis by circular dichroism (CD) and circularly polarized luminescence (CPL) spectroscopies. These findings mark significant strides in the synthesis and characterization of chiral teropyrenes, offering insights into their structural and spectroscopic properties. [ABSTRACT FROM AUTHOR]

An optimized method employing chiral supercritical fluid chromatography with diode array UV–VIS detection has been developed for the quantitative analysis of nicotine and nornicotine enantiomer distributions. The method parameters that were optimized included: column type (stationary phases, Chiralpak IG-3), column temperature (40°C), modifier types and concentration (isopropyl alcohol, 10%), additive types and concentrations (diethylamine, 0.2%), elution times (<6 min, flow rate 3 mL/min) and resolution factor (>1.2). These optimized conditions led to nicotine and nornicotine enantiomer detection limits of ~5 ng/μL with accompanying %RSD values of <2% from the analyses of commercially available nicotine-containing formulations. [ABSTRACT FROM AUTHOR]

A novel analytical method was developed for the simultaneous quantification of the R/S-enantiomers of amphetamine, methamphetamine, MDA and MDMA in hair samples using liquid chromatography-tandem mass spectrometry (LC–MS-MS). This method involved a straightforward derivatization step with dansyl chloride and the use of a chiral column, enabling the separation and quantification of all eight enantiomers in a single analysis. The method exhibited excellent linearity across a concentration range of 0.03–3.00 ng/mg for each enantiomer. Precision and accuracy were within acceptable limits, with bias and relative standard deviation (RSD) values consistently below 6% and 9%, respectively. Selectivity and specificity assessments confirmed the absence of any interference from contaminants or co-extracted drugs. The method demonstrated high sensitivity, with limits of detection (LOD) below 8 pg/mg and limits of quantification (LOQ) below 19 pg/mg for all analytes. Extraction recovery exceeded 79%, and matrix effects were minimal for all analytes. Processed sample stability evaluations revealed consistent results with deviations below 11% for all analytes. Application of the method to 32 authentic human hair samples provided valuable insights into amphetamine use patterns, allowing differentiation between medical amphetamine consumption and illicit use based on enantiomeric composition. Additionally, the method detected co-use of methamphetamine, MDA or MDMA in some samples, highlighting its applicability in drug monitoring and real-life case scenarios within a forensic institute. This innovative analytical approach offers a sensitive and selective method for enantiomeric differentiation of amphetamine, methamphetamine, MDA and MDMA in human hair samples, providing a valuable tool for forensic and clinical investigations. [ABSTRACT FROM AUTHOR]

Amino acids (AAs) including D- and L- enantiomers are a group of organic nitrogen species in ambient aerosol. Due to the low abundances of AAs (level of ng/m3) and the matrix effects by coexistent components, it is challenging to quantify AA enantiomers in ambient aerosols especially under pollution conditions. In this study, we present an optimized method for analyzing AA enantiomers in atmospheric aerosol samples including a pretreatment process and the detection by high performance liquid chromatography coupled to a fluorescence detector (HPLC-FLD). Matrix effects caused by coexistent chemicals on AA enantiomers analysis in ambient aerosol samples were investigated especially for those collected in pollution episodes. The results revealed that the determination of AA enantiomers is significantly affected by the coexistent organic carbon (as a proxy of organic matter) and water-soluble ion of NH 4 +. To remove the matrix effects, we applied a pretreatment using the solid phase extraction column coupled with alkaline adjustment to sample extract. After pretreatment, 18 AAs including 6 pairs of D- and L-enantiomers (i.e., leucine, isoleucine, valine, alanine, serine, and aspartic acid) can be successfully separated and quantified in aerosol samples by HPLC-FLD. The recoveries are in the range of 67%-106%. This method was successfully applied to the urban aerosol samples from pollution and non-pollution periods for AA enantiomers determination. We suggest that the concentrations of D-AAs and the ratio of D-AA/L-AA are indicative of the contribution of bacterial sources and the influence of biomass burning. [ABSTRACT FROM AUTHOR]

The analysis of enantiomers in food has significant implications for food safety and human health. Conventional analytical methods employed for enantiomer analysis, such as gas chromatography and high-performance liquid chromatography, are characterized by their labor-intensive nature and lengthy analysis times. This review focuses on the development of rapid and reliable biosensors for the analysis of enantiomers in food. Electrochemical and optical biosensors are highlighted, along with their fabrication methods and materials. The determination of enantiomers in food can authenticate products and ensure their safety. Amino acids and chiral pesticides are specifically discussed as important chiral substances found in food. The use of sensors replaces expensive reagents, offers real-time analysis capabilities, and provides a low-cost screening method for enantiomers. This review contributes to the advancement of sensor-based methods in the field of food analysis and promotes food authenticity and safety. [ABSTRACT FROM AUTHOR]

Conventional mass spectrometry does not distinguish between enantiomers, or mirror-image isomers. Here we report a technique to break the chiral symmetry and to differentiate enantiomers by inducing directional rotation of chiral gas-phase ions. Dual alternating current excitations were applied to manipulate the motions of trapped ions, including the rotation around the center of mass and macro movement around the center of the trap. Differences in collision cross section were induced, which could be measured by ion cloud profiling at high resolutions above 10,000. High-field ion mobility and tandem mass spectrometry analyses of the enantiomers were combined and implemented by using a miniature ion trap mass spectrometer. The effectiveness of the developed method was demonstrated with a variety of organic compounds including amino acids, sugars, and several drug molecules, as well as a proof-of-principle ligand optimization study for asymmetric hydrogenation. [ABSTRACT FROM AUTHOR]

Several commercial sources of tobacco-derived nicotine (TDN) and synthetic nicotine (SyN) and a variety of e-cigarette liquids employing either TDN or SyN have been evaluated to determine the enantiomer distributions of R- and S-nicotine and R- and S-nornicotine by chiral supercritical fluid chromatography (chiral-SFC) with UV diode array detection (DAD-UV). The data generated are used to test the mismatched vs. matched hypothesis of Cheethamet al. as a means to distinguish products containing TDN from products with SyN. Two sets of experiments were conducted in this study. The first experiment was conducted on a series of 11 commercial nicotine samples (three characterized as tobacco-derived and eight characterized as synthetic nicotine). The commercial nicotine samples were either from a tobacco-derived nicotine (TDN) source or were synthetic nicotine (SyN). Some of the commercial nicotine samples were nicotine salts. The second experiment was conducted on e-liquids from a set of 11 e-cigarettes. The nicotine in the e-liquids was either from TDN or SyN. The e-liquid samples were differentiated based on the advertised information on the internet or from printed information on the e-cigarette packaging. None of the three commercial TDN samples in the first experiment could be unequivocally characterized as coming from a tobacco source. Five of the eight commercial SyN samples were correctly characterized as SyN based on the matched vs. mismatched nicotine and nornicotine hypothesis of Cheethamet al. In the second experiment, none of the e-liquids characterized as being from TDN sources could be unequivocally characterized as coming from a tobacco source. All of the e-liquids characterized as being from SyN sources were either characterized as equivocal or of uncertain origin based on the matched vs. mismatched nicotine and nornicotine hypothesis of Cheethamet al. These sets of experiments represent an excellent example of the difficulty that the United States Food and Drug Administration is having in trying to determine if TDN or SyN is being used in tobacco products. Even highly advanced chromatographic methods such as chiral-SFC were not able to unequivocally distinguish products with TDN from products with SyN 100% of the time. Other analytical methods such as 14C quantitation of nicotine samples by accelerator mass spectrometry offer a more reliable determinate of nicotine source (TDN vs. SyN) and can be used to identify misbranded products labelled as containing SyN, even though this methodology is more expensive and offered in limited locations. [ABSTRACT FROM AUTHOR]

The aim of this study was to develop a simple, specific, sensitive and precise LC-MS method for the determination of mebeverine enantiomers in pharmaceutical formulations and it was validated as per ICH guidelines. The chromatographic separation was achieved on Phenomenex® Lux Cellulose 1 (250 mm x 4.6 mm i.d, 5μm particle size) column using mobile phase system containing acetonitrile: 10 mM ammonium acetate (85:15) at the flow rate of 0.8 mL/min. In the spectral investigation by LC-MS, the standard solution of Mebeverine showed major peak at m/z of 430.70, which was assigned to the [M+H] ion of Mebeverine. The described method was linear over the range of 15–75 ng /mL for (±) Mebeverine enantiomers with a correlation coefficient (r2 = 0.999). Detection limits and quantification limits of (+) Mebeverine and (-) Mebeverine were found to be 5 ng/mL and 15 ng/mL respectively. The recovery study of mebeverine from tablet formulation was found to be 99.16%. Mebeverine standard solution and mobile phase were found to be stable for at least 48h. The Mebeverine enantiomers were well resolved with mean retention times of about 1.16 min and 1.20 min respectively. The developed method was extensively validated and proved to be robust, accurate, precise, and suitable for analysis of Mebeverine enantiomers in tablet dosage form. [ABSTRACT FROM AUTHOR]

BACKGROUND: The accurate characterization of grapevine cultivars (Vitis vinifera) is crucial for grape growers, winemakers, wine sellers, consumers and authorities, considering that mistakes could involve significant damage to the wine economic system. To avoid any misunderstanding, morphological, molecular and chemical tools are developed to positively identify grape varieties. RESULTS: E‐ε‐viniferin is a stilbene dimer mainly present in the woody part of grapevine and present as a mixture of two enantiomers: (7aR, 8aR)‐(−)‐E‐ε‐viniferin (1) and (7aS, 8aS)‐(+)‐E‐ε‐viniferin (2). In addition to phenotypic and genotypic approaches, a chemotaxonomic method using E‐ε‐viniferin enantiomers as chemical markers of grapevine cultivars was investigated. The isolation and purification of E‐ε‐viniferin enantiomers by preparative high‐performance liquid chromatography (HPLC) and chiral HPLC from 14 red and eight white grapevine cane cultivars enabled us to determine the proportion of each enantiomer and therefore to calculate the enantiomeric excess for each variety. The relative abundance of each E‐ε‐viniferin enantiomer permitted us to distinguish grape varieties, as well as to establish cultivar relationships and patterns through statistical analysis. CONCLUSION: This pioneering work highlighting the enantiomeric excess of E‐ε‐viniferin as a chemical marker of grapevine paves the way for further studies to understand what mechanisms are involved in the production of these enantiomers in grapevine. © 2023 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Afoxolaner is a chiral drug that is commonly used for the treatment and prevention of flea and tick infestations in dogs and cats. The two enantiomers of afoxolaner may have different pharmacokinetic and pharmacodynamic properties, making it important to develop an analytical method for the analysis of the individual enantiomers. Normal phase chiral HPLC is a commonly used method for the separation of chiral compounds, and in this case, the amylose tris(3,5-dimethylphenylcarbamate) (ADMC) column has been selected as the chiral stationary phase (CSP). The mobile phase for normal phase chiral HPLC typically consists of a non-polar solvent and a polar modifier, and the specific conditions for the separation of afoxolaner enantiomers will be discussed in the following sections. The development of a normal phase chiral HPLC method for the analysis of afoxolaner enantiomers is crucial for understanding the pharmacokinetics and pharmacodynamics of this important drug. [ABSTRACT FROM AUTHOR]

Background: At present, the research on achiral drug and pesticide residue detection methods is still the mainstay at home and abroad, and there is still a lack of systematic research on the enantiomeric analysis of chiral drugs and pesticides. Objective: In order to prepare a novel chiral stationary phase, whose "multi-mode" chiral separation chromatographic performance and its utility was verified. Method: An S-(-)-2-benzylamino-1-phenylethanol mono-derivative β-cyclodextrin bonded stationary phase (BzCSP) was prepared based on the "thiol-ene" addition reaction. The chiral compounds including four types of chiral compounds were used as "probes," and their chiral chromatographic properties were evaluated. Furthermore, a new LC-MS/MS method for the determination of the enantiomeric residues of three chiral pesticides in five kinds of fruits and vegetables was established. Results: The study found that the novel stationary phase was suitable for a variety of chromatographic modes (normal phasemode, reversed-phasemode, polar organicmode). The resolutions of hexaconazole (Hex), tebuconazole (Teb), and triticonazole (Trit) enantiomers could be up to 2.31, 1.68, and 1.48, respectively, within 30min under reversed-phase chromatography. Based on the optimal chromatographic andmass spectrum conditions, a new LC-MS/MS quantitative method for the Hex, Teb, and Trit enantiomers was established bymulti-reaction positive ionmonitoring (MRM). The detection limits (LODs) of enantiomers were less than 0.89 mg/kg for Hex, 0.93 mg/kg for Teb, and 0.93 mg/kg for Trit, and the averaged recoveries of enantiomers were in the range of 75.8--106.3% for Hex, 77.4-116.3% for Teb, and 78.7-113.4% for Trit. Themethod had good reproducibility with the RSDs (<5%) for intraday and (<7%) for interday. Conclusions: The established method had the characteristics of good selectivity, high sensitivity, strong resistance to matrix interference, and good reproducibility. It is indicated that the stationary phase prepared by the "thiol-ene" addition reaction is a new type of multi-mode stationary phase, which has a good development value. [ABSTRACT FROM AUTHOR]

Recently, Hu et al. have published a very interesting paper concerning the GC-MS analysis of 2-pentanol enantiomers in four types of Baijiu, a strong alcoholic beverage, which is of importance to Chinese social culture [[1]]. The only issue, which in my opinion is disputable, in the paper by Hu et al. is the ions which were chosen for the identification of the title compounds during the GC-MS analysis, identified on page four: " ...and qualitative ions ( I m i / I z i ) of (R)- and (S)-2-pentanol were 75, 73, and 60 and quantitative ions ( I m i / I z i ) were 51." It has to be stressed that the paper by Hu et al. is interesting and that the presented results may find practical application provided that the ions used for the GC-MS analysis of the title compounds are appropriate. References 1 Hu L., Qiu S., Dai Y., Tian L., Wei C. Determination of 2-pentanol enantiomers via chiral GC-MS and its sensory evaluation in Baijiu. [Extracted from the article]

[Display omitted] • A simple method for simultaneous recognition of d / l -Carn was investigated. • d / l -Carn were mobility separated by their ternary diastereomeric complex by adding Nat and meal ions. • Metal ions in group IA (Li+, Na+, K+, Rb+, Cs+) have separation effects. • Theoretical calculations were performed to elucidate the enantiomeric separation at the molecular level. • The proposed method was applied to l / d -Carn detection in beverage samples and fresh pork. This work presents a straightforward approach to the separation d / l -carnitine (d / l -Carn) using ion mobility–mass spectrometry (IM-MS) and theoretical calculations. Natamycin (Nat) was used as separation reagent to interact with the Carn, metal ions (G) were employed as ligand, the resultant ternary complexes [ d / l -Carn + Nat + G]+ were observed experimentally. IM-MS results revealed that d / l -Carn could be baseline separated via complex formation using Li+, Na+, K+, Rb+, and Cs+, with a maximum peak separation resolution (R p-p) of 2.91; Theoretical calculations were performed to determine the optimal conformations of [ d / l -Carn + Nat + Li/K]+, and the predicted collisional cross section values were consistent with the experimental values. Conformational analysis was used to elucidate the enantiomeric separation of d / l -Carn at the molecular level via the formation of ternary complexes. Furthermore, quantitative analyses for the determination of the enantiomers were established with effective linearity and acceptable sensitivity. Finally, the proposed method was successfully applied in the determination of d / l -Carn in food samples. [ABSTRACT FROM AUTHOR]

Warfarin (WF) is an anticoagulant commonly used for thromboembolism-related diseases.This study aims to assess the pharmacokinetic profile of WF. The stereospecific interaction of S-and R-WF requires quantification of the enantiomer to determine the pharmacokinetic profile. The analysis method of the enantiomers in plasma is developed using an HPLC fluorescence detector with a Chiralcel OD-RH column (4.6 mm × 150 mm i.d., 5 m) and a Chiralcel OD-RH guard column (4.0 mm × 10 mm, 5 m). The separation is conducted using isocratic with acetonitrile mobile phase: Phosphate buffer, pH 2.00 (40:60 v/v), column temperature 40°C, flow rate 1 mL/min, injection volume 50 L. WF is measured at an excitation wavelength of 310 nm and emission of 350 nm. This method results in limit of detection (LOD) values of 18.6 ng/mL and limit of quantitation (LOQ) of 62.01 ng/mL for R-WF and LOD values of 18.61 ng/mL and LOQ of 62.04 ng/mL for S-WF. The results showed a linearity in concentration between 100 and 2500 ng/mL with r2 = 0.9969 and r2 = 0.9991 for R-and S-WF. The validation requirements of selectivity, accuracy, and precision for within and between run with a value of <15% for % relative standard deviation and % diff were achieved. This method can be used in the sample measurement of WF pharmacokinetic studies. [ABSTRACT FROM AUTHOR]

Enantiomeric resolution of the drug and complete separation from its degradation products was successfully achieved on a PAK IG-3 (150 × 4.6 mm i.d., 3 µm particle size) column, using UV detector at a wavelength of 290 nm, with mobile phase consisting of acetonitrile, 20 mM ammonium bicarbonate at the ratio of 95:05 (v/v), and a flow rate of 0.7 mL/min. In order to subjected to stress conditions, the drug has been exposed to alkaline, acidic, neutral, oxidative, and photolytic conditions. The products of degradation were well resolved from the main peak and proved the method's stability-indicating method. The method linear ranged between 10–110 μg/mL and 5–100 μg/mL for (+) and (–) midodrine enantiomers and regression analysis showed a correlation coefficient value (r2) of 0.999. The recovery of the method was found to be in the range of 99.1–101.2%. The detection limit for the (+) and (–) enantiomers was found to be 4 μg/mL and 1 μg/mL, respectively. The HPLC method was validated as per ICH guidelines with respect to specificity, precision, linearity, and robustness. [ABSTRACT FROM AUTHOR]

• Inclusion complexation is favoured by the electron-rich cavities of pillar[5]arene. • Enantioseparation was greatly improved by the chiral imidazole modification and introduction of pillar[5]arene. • The fabricated columns allowed highly selective separation of different enantiomers. • Differences in chiral groups effected interactions during enantioseparation. • The enantioseparation mechanism was further studied by AutoDockTools. Chiral pillar[5]arene-based mesoporous silica, an emerging class of chiral structure, possesses excellent characteristics such as abundant chiral active sites, encapsulated cavity and excellent chiral modification, which make them a promising candidate as new chiral stationary phases (CSPs) in enantioseparation. In this study, two imidazole-containing (S)-1-(4-phenyl-1H-imidazol-2-yl)ethanamine and (S)-Histidinol were respectively modified to bromoethoxy pillar[5]arene-bonded silica to construct new chiral stationary phases (s PIE-BP5-Sil and s Hol-BP5-Sil) for the separation and analysis of enantiomers. The separation conditions such as mobile phase composition, flow rate and temperature were optimized. Under optimal conditions, both s PIE-BP5-Sil and s Hol-BP5-Sil showed good separation performance for different types of enantiomers. Interestingly, s PIE-BP5-Sil and s Hol-BP5-Sil showed better enantioselectivity for chiral aromatic compounds and chiral aliphatic compounds, respectively. This enantioseparation result was closely related to the presence of additional aromatic rings and abundant hydroxyl groups in the side chains of the two chiral groups. In addition, the enantioseparation process was further studied by molecular docking simulation. Therefore, this work provided a new strategy for the preparation and application of imidazolyl-derived pillar[5]arene-based chiral stationary phases, which can be efficiently used for screening and separating enantiomers. [ABSTRACT FROM AUTHOR]

An enantiomeric separation of meclizine enantiomers by liquid chromatography with tandem mass spectrometry LC-MS method was developed and validated for the analysis of Meclizine enantiomers. Enantiomeric resolution of the drug products were successfully achieved on a Phenomenex® lux cellulose 1 C18 (250 mm × 4.6 mm i.d, 5 µm particle size) column with mobile phase consisting of acetonitrile: 5 mM ammonium format pH (5.5) adjusted with formic acid (90:10) (v/v), and a flow rate of 0.4 mL/min. The developed method provided linear responses within the concentration range 1–5 ng/mL, and regression analysis showed a correlation coefficient value (r2) of 0.999. The optimized mobile phase separated (+) Meclizine at 1.58 min and (-) Meclizine at 2.20 min, respectively. The LC/MS method was validated as per ICH guidelines with respect to specificity, precision, linearity and robustness. Limit of detection (LOD) and limit of quantification (LOQ) were found to be 1.0 ng/mL and 5.0 ng/mL respectively. The proposed method is suitable for analysis of meclizine enantiomers in pharmaceutical formulations and quality control analysis. [ABSTRACT FROM AUTHOR]

The genus Mentha has been known as culinary source of minty note. Besides, the essential oil imparts value to consumer products like confectionery, cosmetics, and pharmaceutical preparations. A simple and sensitive enantioselective gas chromatographic method is described for the quantitative analysis of terpenoid enantiomers in essential oils using different cyclodextrin coated stationary phases. Limonene, menthone, menthol, and menthyl acetate were identified as pure (-)-enantiomers whereas isomenthone, neomenthol, pulegone, and piperitone as pure (+)-enantiomers in menthol mint, and peppermint oils, respectively. The selectivity of each enantiomer was also demonstrated. A β-cyclodextrin phase with diethyl substitution provides baseline resolution for all target enantiomers with selectivity ranged from 1.004 to 1.050. Moreover, permethylated or diacetylated-β-cyclodextrin showed no selectivity for (+/-)-menthol enantiomers. The current study may facilitate the origin authentication studies of mint oils. Investigation of enantiomers involved in menthol biosynthesis revealed that only (-)-menthol is present in the essential oils of Mentha species. [ABSTRACT FROM AUTHOR]

Oxathiapiprolin is the first chiral piperidinyl thiazole isoxazoline fungicide developed to control downy mildew and other diseases, and there were no prior reports on its enantiomeric residue. In this study, a modified quick, easy, cheap, effective, rugged, and safe extraction and purification method followed by ultra‐high performance liquid chromatography–tandem mass spectrometry determination was first developed and validated for the residue analysis of oxathiapiprolin enantiomers and its metabolite IN‐E8S72 in green tea and other crops. Oxathiapiprolin enantiomers and IN‐E8S72 were separated on a chiral Lux Cellulose‐3 column with the use of 0.1% formic acid in acetonitrile and 5 mmol/L ammonium acetate in water as mobile phases. IN‐E8S72 was eluted first, followed by (−)‐oxathiapiprolin, and then (+)‐oxathiapiprolin. The recoveries ranged from 53.3 to 125.3% with relative standard deviations ranging from 1.4 to 16.0%. The limits of quantification for (−)‐oxathiapiprolin and (+)‐oxathiapiprolin were 0.005 mg/kg in romaine lettuce, head cabbage, potato, grape, and garlic, 0.01 mg/kg in soybean and pea, and 0.025 mg/kg in green tea and dry pepper. The limits of quantification of IN‐E8S72 were twice those of (−)‐oxathiapiprolin. Screening results with real market samples indicated that there was no enantiomeric excess in the oxathiapiprolin residue in romaine lettuce. [ABSTRACT FROM AUTHOR]

Professor William H. Pirkle (1934–2018) made a profound impact on modern chemistry by inventing and popularizing widely used techniques for the analysis and purification of enantiomers, contributions that paved the way for the subsequent advances in the discovery, development, and manufacture of enantiopure pharmaceuticals, agrochemicals, and specialty chemicals. Pirkle's pioneering 1966 demonstration of the use of chiral solvating agents for the nuclear magnetic resonance determination of enantiopurity led to a lifelong interest in understanding the supramolecular interactions responsible for enantiodifferentiation. Ongoing research into the chromatographic resolution of stereoisomers throughout the 1970s led in 1981 to the very first commercialization of a chiral stationary phase for the high‐performance liquid chromatography (HPLC) separation of enantiomers. The availability of this and subsequent "Pirkle columns" had a deep and lasting impact, becoming widely embraced by the chemical sciences research community worldwide and spearheading the wholesale changeover to HPLC as the preferred technique for measuring enantiopurity. Doc Pirkle was a highly creative, independent, and fun‐loving collaborator whose circle of friends extends around the globe. His research group at the University of Illinois, often referred to as The Pirkle Zoo, became a refuge for an interesting assembly of characters who flourished under his mentorship and guidance. [ABSTRACT FROM AUTHOR]

In this work, two chiral methods enabling the separation of ibrutinib enantiomers were developed by Electrokinetic Chromatography. A cyclodextrin (CD) or a mixture of the CD and a chiral ionic liquid (CIL) was used as chiral selector. Using the single CD system, seven neutral and six anionic CDs were tested in a formate buffer at pH 3.0 working in positive and negative polarity, respectively. The use of sulfated-γ-CD (S-γ-CD) and negative polarity originated the best results considering analysis time and enantioresolution. The optimization of the experimental conditions allowed obtaining the separation of ibrutinib enantiomers in an analysis time of 4.2 min with an enantioresolution value of 1.5. The effect of the addition of fifteen CILs on the enantioresolution was evaluated showing that both analysis time and enantioresolution were generally increased. A mixture of S-γ-CD and [TMA][L-Lys] was selected which provided the separation of ibrutinib enantiomers in 8.1 min with an enantioresolution value of 3.3 under the same experimental conditions as in the case of using the single CD system. The enantiomeric impurity (S-ibrutinib) was the first-migrating isomer when using the single CD and the combined CD/CIL systems, as corresponds to the most desirable situation. Both chiral methods allowed the detection of the enantiomeric impurity up to a 0.1% as established by the International Council on Harmonization. After establishing the analytical characteristics of both chiral methodologies developed, they were applied to the enantiomeric determination of ibrutinib in a pharmaceutical formulation for hospital use marketed as pure enantiomer (R-ibrutinib) and to evaluate the stability and ecotoxicity of racemic ibrutinib and R-ibrutinib on Daphnia magna. The developed methodologies enabled, for the first time, the rapid chiral quantitation of ibrutinib in abiotic and biotic matrices. [Display omitted] • Enantioseparation of ibrutinib by EKC using a CD and its combination with a CIL. • Both methods allowed the detection of a 0.1% of the enantiomeric impurity. • First quantitative chiral analysis of ibrutinib in a pharmaceutical formulation. • Stability and ecotoxicity evaluation of R,S- and R-ibrutinib on Daphnia magna. • R,S-ibrutinib showed higher toxicity than R-ibrutinib on Daphnia magna. [ABSTRACT FROM AUTHOR]

A quick, green, and sensitive method for chiral separation and determination of fluazifop‐butyl enantiomers in tobacco and soil was established by ultra‐performance convergence chromatography with tandem mass spectrometry (UPC2‐MS/MS). The baseline separation was obtained on an ACQUITY UPC2 Trefoil CEL2 column in 4 minutes with CO2 and methanol as mobile phase. Column temperature, auto back pressure regulator pressure (ABPR), and modifier solvent were optimized to obtain the best separation efficiency. Under the optimal conditions, the recoveries of both enantiomers were 82.8% to 99.5% with relative standard deviations (RSDs) less than 5.5% at three different concentration levels in two matrices. Good coefficients of determination (R2 ≥ 0.9976) were achieved over the concentration range of 10 to 500 ng/mL. The limits of detection (LODs) for all enantiomers in the two matrices varied from 1.6 to 2.1 μg/kg, and the limits of quantification (LOQs) did not exceed 7.0 μg/kg. The proposed method was then successfully applied to analyze authentic samples, confirming that it was a green, convenient, and reliable strategy for the analysis of fluazifop‐butyl enantiomers in tobacco and soil. [ABSTRACT FROM AUTHOR]

Compounds with activity at serotonin (5‐hydroxytryptamine) 5‐HT2 and α1 adrenergic receptors have potential for the treatment of central nervous system disorders, drug addiction or overdose. Isolaureline, dicentrine and glaucine enantiomers were synthesized, and their in vitro functional activities at human 5‐HT2 and adrenergic α1 receptor subtypes were evaluated. The enantiomers of isolaureline and dicentrine acted as antagonists at 5‐HT2 and α1 receptors with (R)‐isolaureline showing the greatest potency (pKb = 8.14 at the 5‐HT2C receptor). Both (R)‐ and (S)‐glaucine also antagonized α1 receptors, but they behaved very differently to the other compounds at 5‐HT2 receptors: (S)‐glaucine acted as a partial agonist at all three 5‐HT2 receptor subtypes, whereas (R)‐glaucine appeared to act as a positive allosteric modulator at the 5‐HT2A receptor. The (R)‐ and (S)‐enantiomers of isolaureline and dicentrine act as antagonists at 5‐HT2 and α1 receptors with (R)‐isolaureline showing the greatest potency (pKb = 8.14 at the 5‐HT2C receptor). Both (R)‐ and (S)‐glaucine also antagonize α1 receptors, but the two enantiomers behave very differently at 5‐HT2 receptors: (S)‐glaucine acts as a partial agonist at all three 5‐HT2 receptor subtypes, whereas (R)‐glaucine appears to act as a positive allosteric modulator at the 5‐HT2A receptor. [ABSTRACT FROM AUTHOR]

Abstract Two novel chiral 3,4-dihydro-2 H -thieno[3,4- b ][1,4]dioxepine (ProDOT)-based electrochemical sensor, employing a pair of glassy carbon electrodes modified with chiral poly(2-Phenyl-propionic acid 3,4-dihydro-2 H -thieno[3,4- b ][1,4]dioxepin-3-ylmethyl ester) (PProDTM-PP), were utilized for the enantioselective detection of chiral 3,4-dihydroxyphenylalanine (DOPA). The enantioselective recognition between chiral PProDTM-PP modified glassy carbon electrodes and chiral DOPA was studied by using different electrochemical technologies. The redox activity and electrochemical stability of chiral PProDTM-PP was good. (R)-PProDTM-PP and (S)-PProDTM-PP showed higher peak current responses toward D -DOPA and L -DOPA, respectively. Furthermore, the recognition efficiencies of chiral PProDTM-PP are between 1.48 and 1.89, which is higher than chiral PEDOT-based electrochemical sensors (around 1.10). The chiral PProDTM-PP provides an alternative to chiral recognition. [ABSTRACT FROM AUTHOR]

Chiral analysis is of pivotal importance in a variety of fields due to the different biological activities and functions of enantiomers. Here, we develop a simple paper-based chiral biosensor that can perform sample-to-answer simultaneous analysis of lactate enantiomers in human serum samples. By modification of alginate hydrogel with "egg-box" three-dimensional network structure on a glass microfiber paper, reagents of enantiomer-selective enzymatic reactions are efficiently encapsulated forming the sensing regions for chiral analysis. Dual enzyme catalytic system (lactate dehydrogenase and glutamic pyruvic transaminase) is utilized to enhance the response of the biosensor. A smartphone with color analysis software is used to collect and analyze the fluorescence signal from the product nicotinamide adenine dinucleotide. The results show that the sensor has excellent selectivity toward lactate enantiomers with low limit-of-detection of (30.0 ± 0.7) μM for L-lactate and (3.0 ± 0.2) μM for D-lactate, and wide linear detection range of 0.1–3.0mM and 0.01–0.5 mM for L-lactate and D-lactate respectively. The proposed method is successfully applied to the simultaneous detection of L-/D-lactate concentrations in human serum with satisfactory accuracy. Our study provides a robust approach for developing chiral biosensors, which would have promising application prospect in point-of-care testing (POCT) analysis of various biological and food samples. [Display omitted] • Sample-to-answer simultaneous analysis of lactate enantiomers. • Dual enzyme catalytic system to enhance the response of the paper-based sensor. • Excellent reproducibility and selectivity of lactate enantiomers for POCT. [ABSTRACT FROM AUTHOR]

• Enantioseparation of quizalofop-ethyl and its acid metabolite on a cellulose-based chiral column. • Liquid-solid extraction from soil and vegetable samples contaminated by quizalofop-ethyl. • Thermodynamic study on the enantioseparation to set the best separation conditions. • Quantitative analysis of quizalofop-ethyl enantiomers in vegetables via HPLC-MS\MS. • Diffusive dynamics of quizalofop-ethyl and its metabolite in the selected samples. In this study, the attention was focused on quizalofop-ethyl, a chiral herbicide whose formulation has recently been marketed as quizalofop-P-ethyl, i.e. the (+)-enantiomer exhibiting herbicidal activity. To verify the real enantiomeric purity of this product as well as to study its environmental fate, the enantioselective separation of the P- and M- enantiomers of quizalofop-ethyl was achieved on Lux Cellulose-2 column (3‑chloro,4-methylphenilcarbamate cellulose) under isocratic conditions in polar organic mode. Once established that the commercial formulation contains ˜ 0.6% (enantiomeric fraction) of M as an impurity, an HPLC-MS/MS method was developed, validated and applied to the analysis of soil, carrots and turnips treated with the herbicide. A simple solid-liquid extraction allowed recoveries greater than 70%; limits of detections of P and M enantiomers were below 5 ng g−1. The analyses of the real samples showed a modification of the enantiomeric fraction of quizalofop-M-ethyl between the commercial formulation (EF M = 0.63 ± 0.03%) and the analysed matrices (EF M = 7.6 ± 0.1% for carrots; EF M = 0% for the other matrices). This outcome highlighted the occurrence of an enantioselective biotic dissipation, responsible for a greater persistency of the distomer in carrots. On the other hand, since screening analyses revealed the occurrence of residues of the metabolite quizalofop-acid with the same EFs as the ester precursor, it was concluded that the hydrolytic conversion was an abiotic process. [ABSTRACT FROM AUTHOR]

The combination of enzymatic and chemical reaction steps is one important area of research in organic synthesis, preferentially as cascade reactions in one‐pot to improve total conversion and achieve high operational stability. Here, the combination of the Suzuki–Miyaura reaction is described to synthesize biaryl compounds followed by a transamination reaction. Careful optimization of the reaction conditions required for the chemo‐ and biocatalysis reaction enabled an efficient two‐step‐one‐pot reaction yielding the final chiral amines with excellent optical purity (>99 % ee) in up to 84 % total conversion. Key to the success was the protein engineering of the amine transaminases from Asperguillus fumigatus (4CHI‐TA) where single alanine mutations increased the conversion up to 2.3‐fold. Finally, the transfer to a continuous flow system after immobilization of the best 4CHI‐TA variant is demonstrated. The combination of amine transaminase (ATA) activity and the Suzuki–Miyaura cross‐coupling reaction in a two‐step‐one‐pot fashion is presented. The biaryl amines were obtained with high conversion and excellent enantiomeric excess (99 % ee) using isopropylamine as the amine donor after engineering of the transaminase from Asperguillus fumigatus. [ABSTRACT FROM AUTHOR]

A reversed‐phase simultaneous determination method for the enantiomers of carfentrazone‐ethyl and its metabolite carfentrazone in agricultural and environmental samples was established using high‐performance liquid chromatography‐tandem mass spectrometry. A complete enantioseparation of carfentrazone‐ethyl and its chiral metabolite carfentrazone enantiomers was obtained using a chiral column. The absolute configuration and specific optical rotation of carfentrazone‐ethyl and carfentrazone enantiomers were first confirmed as peaks 1, 2, 3, and 4: S‐(+)‐carfentrazone, R‐(‐)‐carfentrazone, S‐(‐)‐carfentrazone‐ethyl, and R‐(+)‐carfentrazone‐ethyl, respectively. The specificity, matrix effect, linearity, precision, accuracy, and stability were surveyed to evaluate the feasibility of the method. The mean recovery was in the range of 77.5–102.8% with relative standard deviations of 0.4‐9.8% for the samples. The limits of detection of the enantiomers were evaluated as 0.7 to 6.0 μg/kg, and the limits of quantification were 2.5 to 20 μg/kg. The stereoselective degradation of carfentrazone‐ethyl and carfentrazone in rice plant was investigated, and there was no clear enantioselectivity for carfentrazone‐ethyl. As for carfentrazone, the enantiomer fractions value reached 0.85 at 7 days after spraying. The developed method was simple and reliable enough for the corresponding risk assessment of carfentrazone‐ethyl and its metabolite enantiomers in crop plants, cereal grains, and soil samples. [ABSTRACT FROM AUTHOR]

The ketone body ester (R)-3-hydroxybutyryl-(R)-3-hydroxybutyrate and its (S,S) enantiomer were prepared in a short, operationally simple synthetic sequence from racemic β-butyrolactone. Enantioselective hydrolysis of β-butyrolactone with immobilized Candida antarctica lipase-B (CAL-B) results in (R)-β-butyrolactone and (S)-β-hydroxybutyric acid, which are easily converted to (R) or (S)-ethyl-3-hydroxybutyrate and reduced to (R) or (S)-1,3 butanediol. Either enantiomer of ethyl-3-hydroxybutyrate and 1,3 butanediol are then coupled, again using CAL-B, to produce the ketone body ester product. This is an efficient, scalable, atom-economic, chromatography-free, and low cost synthetic method to produce the ketone body esters. [ABSTRACT FROM AUTHOR]

Crossed aldol reactions of the CF3-containing pseudo C2 symmetric cyclic imide 3 were carried out by way of the corresponding boron bisenolate to stereoselectively furnish the desired products 4 and this procedure allowed the preferential construction of the diastereomers of the compounds previously obtained from the acyclic counterpart 1. [ABSTRACT FROM AUTHOR]

AIE-active chiral polymer enantiomers (S-/R-P) can emit green circularly polarized electroluminescence (CP-EL) with gEL up to 0.024 without alignment layers and chiral dopants, which represents the first example of CP-OLEDs based on AIE-active main-chain chiral polymers. [ABSTRACT FROM AUTHOR]

The CHIRALPAK-IC was used, and the mixed solution of V (re-hexane) : V (isopropanol) = 95 : 5 was used as the mobile phase, and diethylamine was used as the mobile phase additive. In normal phase chromatography mode, a chiral column-high performance liquid chromatography-diode array detector (HPLC-DAD ) method was developed for the separation and analysis of nicotine optical isomers in tobacco and tobacco products. The characterization and test results of this method indicated:) The linear relationship between S-( -)-nicotine and R-( +)-nicotine was in the range of 15 ~750 µg/mL and 0. 75 ~30. 00 µg/mL, respectively. The detection limit and limit of quantification were 0.2 mg/g and 0. 05 mg/g, respectively. 2) The precision of intra- and inter-day measurements of nicotine was less than 0. 85% and 4. 00%, respectively; the recovery rates of S-( - ) -nicotine and R-( + ) -nicotine were 94. 93% ~ 103. 70% and 92. 50% ~ 117. 50%, respectively. This indicated that the method had good precision and high recovery rate. Using this method to determine the nicotine optical isomers of 26 different types of tobacco and tobacco products, it was found that tobacco was mainly S-( - )-nicotine, only 6 samples were detected by R-( + )-nicotine. The proportion of nicotine quality was 0. 18% ~0.70% ; among the 10 finished cigarettes and their mainstream smoke, the proportion of R-( + )-nicotine in total cigarette smoke was higher than that of cigarette tobacco. [ABSTRACT FROM AUTHOR]

Herein, we developed a rapid supercritical fluid chromatography (SFC) method for chiral separation and enantioselective determination of prothioconazole in soil and tomatoes. The potential effects of chiral stationary phases, co-solvents, column temperature, and back pressure on enantioseparation of prothioconazole have been studied in detail. Two prothioconazole enantiomers were best separated on cellulose tris(3, 5-dimethylphenylcarbamate)-coated chiral stationary phase with CO 2 -2-propanol (80:20, v/v) as the mobile phase, and the run time through SFC (about 4 min) was five-fold shorter than HPLC. Then, through comparing the experimental vibrational circular dichroism spectrum of the later-eluted component with the calculated pattern based on the ( R )-configuration, it should be ( R )-(-)-prothioconazole. Moreover, the modified QuEChERS (quick, easy, cheap, effective, rugged and safe) extraction and cleanup procedures were applied in enantiomeric analysis of prothioconazole in two matrices. Good linearity ( R 2 ≥ 0.9992) and recoveries (91.84–101.66%, RSD ≤ 3.98%) for two enantiomers were achieved. This proposed method showed good accuracy and precision, and might be suitable for fast enantioselective determination and residual quantitative analysis of prothioconazole in food and environmental samples. [ABSTRACT FROM AUTHOR]

Stereochemical effects during two-dimensional crystallization of bisheptahelicene diastereomers on a Cu(111) surface have been studied with scanning tunnelling microscopy. The (M,M)- and (P,P)-enantiomers crystallize into a monolayer racemate lattice, whereas the (M,P)-diastereomers aggregate into their own monolayer phase. [ABSTRACT FROM AUTHOR]

A novel and simple chiral sensing platform had been successfully fabricated by means of amidation reaction between 3, 4, 9, 10-perylenetetracarboxylic acid (PTCA) and chitosan (CS) to form 3, 4, 9, 10-perylenetetracarboxylic acid-chitosan (PTCA-CS) composite film. Since CS has chiral center and PTCA has excellent electrical conductivity, the PTCA-CS composite modified glassy carbon electrode (PTCA-CS/GCE) could be treated as an effective electrochemical chiral sensor and applied for chiral discrimination of tryptophan (Trp) enantiomers theoretically. PTCA-CS composite was characterized by Fourier transform infrared (FTIR) spectroscopy and cyclic voltammetry (CV). When the prepared chiral sensing interface interacted with tryptophan isomers, a higher selectivity was received from D-Trp by differential pulse voltammetry (DPV). It indicated that the PTCA-CS/GCE can be treated as an electrochemical chiral sensor for the discrimination of Trp enantiomers. Further study demonstrated that the peak currents were linearly increased with the increasing percentage of L-Trp of Trp racemic mixture. Furthermore, the enantioselective interaction of the PTCA-CS/GCE was systematically studied by other experimental factors, such as the incubation time and acidity. [ABSTRACT FROM AUTHOR]

The first experimental application of enantioselective Raman spectroscopy (esR) is demonstrated using the example of the chiral alcohol 2-butanol. Samples of the neat enantiomers and the racemic mixture were analyzed in a self-built Raman set-up. The Raman spectrum allows the discrimination of the chemical species. It is shown that the optical rotation of a Raman peak with a small depolarization ratio can be measured. In addition, without any sample modification, e.g. chiral solvent, the enantiomers are distinguishable at a suitable half-wave retarder angle detecting only the vertically polarized component of the Raman signal. [ABSTRACT FROM AUTHOR]

This work describes the influence of different achiral polymers used to dissolve permethyl-β-cyclodextrin (PM-β-CD) on the gas chromatographic enantioresolution of racemic mixtures of polar pesticides (mecoprop, dichlorprop, fenoprop and hydroprop esters, fenoxaprop ethyl, metalaxyl, and haloxyfop esters). One main objective was to introduce a single column for robust and sensitive enantioseparations of several and different polar pesticides, which have to be chromatographed at relatively high temperature (unfavorable condition for enantiodiscrimination). In particular, the ability of capillary columns coated with PM-β-CD dissolved in either (14%-cyanopropylphenyl)(1%-vinyl)-86%-methylpolysiloxane (OV-1701-vi), (5%-phenyl)(1%-vinyl)-95%-methylpolysiloxane (SE-54) or in polyethyleneglycol (Carbowax 20 M), to resolve the racemates of the aforementioned pesticides was evaluated. An analogous commercial column, Hydrodex β-PM, was taken as reference. In addition, the influence of the achiral polymer in the availability of selector for enantioselective interactions with those pesticides was studied. Enantioseparations achieved with the phase based on the less polar polysiloxane SE-54 were higher for most chiral pesticides as compared with those obtained with PM-β-CD mixed in more polar polymers. The results furthermore indicate that a single column based on PM-β-CD/SE-54 exhibited great potential for application in the separation of a wide variety of polar pesticides and their derivatives. [ABSTRACT FROM AUTHOR]

Abstract: The reaction of chiral sodium complexes, 1∞[Na(S‐valmetH)]⋅H2O (1‐S) and 1∞[Na(R‐valmetH)]⋅H2O (1‐R), with copper(II) acetate affords chiral one‐dimensional coordination polymers with the formulas 1∞[Cu(S‐valmet)(H2O)]⋅H2O (2‐S) and 1∞[Cu(R‐valmet)(H2O)]⋅H2O (2‐R) (R/S‐valmetH2 are Schiff base proligands resulting from the condensation reactions between o‐vanillin and R/S‐methionine). The copper ions are connected by the carboxylato groups belonging to the amino‐acid moieties, resulting in infinite chains showing syn‐anti out‐of‐plane bridging mode. The circular dichroism spectra of 1‐S, 1‐R, 2‐S, and 2‐R confirm their enantiomeric nature. Compounds 2‐S and 2‐R undergo a two‐step single‐crystal‐to‐single‐crystal transformation, with the elimination of the lattice and coordinated water molecules: 1∞[Cu(S‐valmet)(H2O)]⋅H2O (2‐S)→1∞[Cu(S‐valmet)]⋅H2O (3‐S⋅H2O)→1∞[Cu(S‐valmet)] (3‐S) and 1∞[Cu(R‐valmet)(H2O)]⋅H2O (2‐R)→1∞[Cu(R‐valmet)]⋅H2O (3‐R⋅H2O)→1∞[Cu(R‐valmet)] (3‐R), respectively. During these transformations, every pair of face‐to‐face chains present in 2‐S (or 2‐R) has been “zipped up” into a chiral double chain through the removal of the aqua ligands and their replacement by the carboxylato oxygen atoms from the neighboring chain. Consequently, each carboxylato group now bridges three copper ions. The conversion of the single chains, 2‐S and 2‐R, into the double chains, 3‐S and 3‐R, is accompanied by a change of the strength of the exchange interactions between the copper ions: weak antiferromagnetic couplings are observed in compound 2‐S (J/kB=−1.23(5) K, H=−2J ΣSiSi+1) and relatively strong in compound 3‐S (J/kB=−76.0(8) K). When the racemic mixture of the ligands, R,S‐valmetH2, is employed, in the same experimental conditions, a racemic mixture of mononuclear compounds, [Cu(R,S‐valmet)(H2O)2]⋅H2O (4‐RS), is obtained. Compound 4‐RS also undergoes a SCSC transformation with the elimination of the lattice and one of the coordinated water molecules, resulting in a racemic mixture of chiral chains, 1∞[Cu(R‐valmet)(H2O)]⋅1∞[Cu(S‐valmet)(H2O)] (5‐RS). In this compound, the coupling of the copper(II) ions within the chains is weak and ferromagnetic (J/kB=+0.10(2) K). These results prove that the chirality of the valmetH2 ligands (optically pure or racemic mixture) plays a key role in the self‐assembly process of the copper(II) complexes. [ABSTRACT FROM AUTHOR]

A new approach to not-readily-available optically active tertiary propargylic alcohols through palladium/H+-cocatalyzed carboxylation of racemic tertiary propargylic alcohols with CO and MeOH has been described. Both enantiomers can be obtained with no less than 90% ee utilizing (R) or (S)-DTBM-Segphos. Various transformations of the optically active alcohols have been demonstrated. [ABSTRACT FROM AUTHOR]

Abstract: Fluoroquinolones are popular class of antibiotics with distinct chemical functionality. Most of them are ampholytes with one chiral center. Stereogeneic center is located either in the side ring of Gatifloxacin (GFLX) or in the quinolone core of Ofloxacin (OFLX). These two amphoteric fluoroquinolones have terminal amino groups in common. The unusual Nadifloxacin (NFLX) is an acidic fluoroquinolone with a core chiral center. Owing to chirality and functionality differences among GFLX, OFLX, and NFLX, we mapped these enantiomers onto structure‐retention relationship. Amount of acetic acid modifier was studied in screened mobile phase and cellulose tris(3‐chloro‐4‐methyl phenyl carbamate) (Lux cellulose‐2) stationary phase. Experimental design of acetic acid% along with column temperature have been applied. Resolution and enantioselectivity have been related to structural features of the studied enantiomers. High amount of acid (0.4%) was optimum for the separation of either side chirality with a proximate amino group (GFLX) or core chirality without basic functionality (NFLX), while low amount (0.2%) is optimum for core chiral center with distal amino group (OFLX). Temperature has no significant effect on resolution and retention of enantiomers except for OFLX. Enantio‐retention explains possible chiral selective and nonselective interactions. The proposed methods have been validated for pharmaceutical analyses. [ABSTRACT FROM AUTHOR]

Abstract: Terbutaline is a β2‐adrenoceptor agonist for the treatment of asthma and chronic obstructive pulmonary disease (COPD). Among the two isomers of terbutaline (TBT 2), R‐isomer was found to be the potent enantiomer in generating therapeutic effect, while S‐isomer has been reported to show side effects. In this study, R‐terbutaline hydrochloride (R‐TBH 6) was synthesized through chiral resolution from the racemic terbutaline sulfate (rac‐TBS 1) with 99.9% enantiomeric excess (ee) in good overall yield (53.6%). Further, R‐TBH 6 nebulized solution was prepared in half dosage of Bricanyl®, which is a marketed product of racemic terbutaline and evaluated in vitro aerosol performance and in vivo anti‐asthmatic effect on guinea pigs via. pulmonary delivery. From the investigation, it is evident that R‐TBH 6 nebulized solution of half dosage performed similar fine aerosol characteristics and anti‐asthmatic effect with Bricanyl®. [ABSTRACT FROM AUTHOR]

Owing to enantiomers’ identical physical and chemical properties, separation work in the chiral environments is still a great challenge.and chemical properties. Chromatographic techniques employing chiral stationary phases (CSPs) have been developed as powerful tools for the chiral analysis and preparation of pure enantiomers. Here we report a facile synthesis of vancomycin stationary phase based on diazotized silica. Monodisperse silica particles were synthesized by a modified Stöber method. The obtained silica particles were modified by self-assembly photosensitive diazoresin (DR) and vancomycin on the surface. After treatment with UV light, the ionic bonding was converted into covalent bonding through a unique photochemistry reaction of DR. Baseline separation of chiral drugs was achieved by using the vancomycin@SiO 2 particles as packing materials in high performance liquid chromatography (HPLC). The effects of separation parameters including elution mode, flow rate and analyte mass on the enantioselectivity of the CSP were investigated in detail. Due to the replacement of highly toxic and moisture sensitive silane agent by water soluble non-toxic DR in the modification of silica microspheres, this method provides a green and easy way to manufacture packing materials for chromatography applications. [ABSTRACT FROM AUTHOR]

Although stereoselective antibody has immense potential in chiral compounds detection and separation, the interaction traits between stereoselective antibody and the corresponding antigenic enantiomers are not yet fully exploited. In this study, the stereospecific interactions between ofloxacin isomers and corresponding monoclonal antibodies (McAb-WR1 and McAb-MS1) were investigated using time-resolved fluorescence, steady-state fluorescence, and circular dichroism (CD) spectroscopic methods. The chiral recognition discrepancies of antibodies with ofloxacin isomers were reflected through binding constant, number of binding sites, driving forces and conformational changes. The major interacting forces of McAb-WR1 and McAb-MS1 chiral interaction systems were hydrophobic force and van der Waals forces joined up with hydrogen bonds, respectively. Synchronous fluorescence spectra and CD spectra results showed that the disturbing of tyrosine and tryptophan micro-environments were so slightly that no obvious secondary structure changes were found during the chiral hapten binding. Clarification of stereospecific interaction of antibody will facilitate the application of immunoassay to analyze chiral contaminants in food and other areas. [ABSTRACT FROM AUTHOR]

In this work, we report the synthesis of a novel, green and recoverable organic-inorganic magnetic nanocomposite by grafting β-cyclodextrin on the surface of a silica-coated magnetic nanoparticle, Fe3O4@SiO2/Pr-β-CD. FT-IR spectroscopy, transmission electron microscopy, CHN analysis, thermogravimetric analysis, vibrating sample magnetometer and X-ray diffraction analyses confirmed its structure. The magnetic core-shell structured modified silica microsphere has been successfully used as a chiral micro-vessel catalyst for the enantioselective reduction of ketones by NaBH4. The described catalyst was regenerated and reused without any significant changes in the yield and enantiomeric excess. [ABSTRACT FROM AUTHOR]

Abstract: A robust and sensitive method was developed for the enantiomeric analysis of six chiral pesticides (including metalaxyl, epoxiconazole, myclobutanil, hexaconazole, napropamide, and isocarbophos) in aquatic environmental samples. The optimized chromatographic conditions for the quantification of all the 12 enantiomers were performed with Chiralcel OD‐RH column using mobile phase consisting of 0.1% aqueous formic acid and acetonitrile operated under reversed‐phase conditions and then analyzed using liquid chromatography with tandem mass spectrometry. Twelve enantiomers were detected in multiple reaction monitoring mode. Solid‐phase extraction and dispersive liquid–liquid microextraction were employed in this study. Response surface methodology was applied to assist in the dispersive liquid–liquid microextraction optimization. Under the optimum conditions, recoveries of pesticides enantiomers varied from 83.0 to 103.2% at two spiked levels with relative standard deviation less than 11.5%. The concentration factors were up to 1000 times. Method detection and quantification limits varied from 0.11 to 0.48 ng/L and from 0.46 to 1.49 ng/L, respectively. Finally, this method was used to determination of the enantiomers composition of the six pesticides in environmental aqueous matrices, which will help better understand the behavior of individual enantiomer and make accurate risk assessment to ecosystems. [ABSTRACT FROM AUTHOR]

Abstract: Thirteen pairs of enantiomers belonging to the same structural family (phenylthiohydantoin‐amino acids) were analyzed on two polysaccharide chiral stationary phases, namely, tris‐(3,5‐dimethylphenylcarbamate) of amylose (Chiralpak AD‐H) or cellulose (Chiralcel OD‐H) in supercritical fluid chromatography with a carbon dioxide/methanol mobile phase (90:10 v/v). Five different temperatures (5, 10, 20, 30, 40°C) were applied to evaluate the thermodynamic behavior of these enantioseparations. On the cellulose stationary phase, the retention, and separation trends were most similar among the set of probe analytes, suggesting that the chiral cavities in this stationary phase have little diversity, or that all analytes accessed the same cavities. Conversely, the retention and separation trends on the amylose phase were much more diverse, and could be related to structural differences among the set of probe analytes (carbon chain length in the amino acid residue, secondary amine in proline, existence of covalent rings, or formation of pseudo‐rings via intramolecular hydrogen bonds). The large variability of behaviors on the amylose phase suggests that the chiral‐binding sites in this chiral stationary phase have more variety than on the cellulose phase, and that the analytes did access different cavities. [ABSTRACT FROM AUTHOR]

Abstract: Dextromethorphan is a centrally acting antitussive drug, while its enantiomer levomethorphan is an illicit drug with opioid analgesic effects. As capillary electrophoresis has been proven as an ideal technique for enantiomer analysis, the present study was conducted in order to develop a capillary electrophoresis‐based limit test for levomethorphan. The analytical target profile was defined as a method that should be able to determine levomethorphan with acceptable precision and accuracy at the 0.1 % level. From initial scouting experiments, a dual selector system consisting of sulfated β‐cyclodextrin and methyl‐α‐cyclodextrin was identified. The critical process parameters were evaluated in a fractional factorial resolution IV design followed by a central composite face‐centered design and Monte Carlo simulations for defining the design space of the method. The selected working conditions consisted of a 30/40.2 cm, 50 μm id fused‐silica capillary, 30 mM sodium phosphate buffer, pH 6.5, 16 mg/mL sulfated β‐cyclodextrin, and 14 mg/mL methyl‐α‐cyclodextrin at 20°C and 20 kV. The method was validated according to ICH guideline Q2(R1) and applied to the analysis of a capsule formulation. Furthermore, the apparent binding constants between the enantiomers and the cyclodextrins as well as complex mobilities were determined to understand the migration behavior of the analytes. [ABSTRACT FROM AUTHOR]

The first catalytic enantioselective C(sp)--C(sp³) cross-coupling reaction between N-tosylhydrazones and trialkylsilylethynes in the presence of Cu(I) salts and chiral phosphoramidite ligands was developed. A series of synthetically interesting, functionalized alkynes were obtained with moderate to good enantioselectivities (up to 83% ee). Cu(II) carbene migratory insertion is proposed to be the enantio-determining step. [ABSTRACT FROM AUTHOR]

Hemoglobin (Hb) adducts of acrylamide (AA) and its oxidative metabolite glycidamide (GA) are important biomarkers for evaluating the mid-term exposure of acrylamide toxicity in vivo. Taking pentafluoro-2-methylphenyl isothiocyanates of N-(2-carbamoylethyl)valine (AAVal-PFPTH) and N-(2-carbamoyl-2-hydroxyethy)valine (GAVal-PFPTH) as target analytes, we developed an isotope dilution ultra-high performance liquid chromatograph tandem mass spectrometry (UHPLC-MS/MS) method for the simultaneous determination of AA and GA hemoglobin (Hb) adducts under the electroscopy ionization negative (ESI‾) mode in the present work. Among them, the enantiomer pair of GA-Hb adducts was firstly identified and successfully separated at baseline level. The method achieved high sensitivity with the LOD and LOQ ranging 1.43–5.05 pmol/g Hb and 4.78–16.82 pmol/g Hb, respectively. The recovery rates with low, intermediate and high spiking levels were calculated as 97.0–105.2%, 97.4–106.4% and 100.3–111.2%, respectively. Acceptable within-laboratory reproducibility (RSD < 13.7%) substantially supported the robustness of current UHPLC-MS/MS method, which was successfully applied to measure the hemoglobin adducts of acrylamide and glycidamide enantiomers in blood of both rats and humans. A linear exposure assessment model was developed for estimating the daily exposure to acrylamide in humans via considering acrylamide hemoglobin adducts as variables, indicating a novel connect between biomarker-based internal exposure and dietary-based external exposure. Overall, the present instrumental analysis and related internal exposure assessment model provide a substantially methodological support for profiling the internal biological exposure and estimating the external dietary exposure to acrylamide. [ABSTRACT FROM AUTHOR]

Abstract: Piperonyl ring is found in a number of naturally occurring compounds and possesses enormous biological activities. There are many studies in the literature with compounds containing a piperonyl ring, but there are very few studies on the synthesis of chiral piperonyl carbinol. The objective of this study was to determine the microbial reduction ability of bacterial strains and to reveal the effects of different physicochemical parameters on this reduction ability. A total of 15 bacterial isolates were screened for their ability to reduce 1‐(benzo[d][1,3]dioxol‐5‐yl) ethanone 1 to its corresponding alcohol. Among these isolates Lactobacillus paracasei BD101 was found to be the most successful biocatalyst to reduce the ketone containing piperonyl ring to the corresponding alcohol. The reaction conditions were systematically optimized for the reducing agent L paracasei BD101, which showed high enantioselectivity and conversion for the bioreduction. The preparative scale study was performed, and a total of 3.72 g of (R)‐1‐(1,3‐benzodioxol‐5‐yl) ethanol in high enantiomeric form (>99% enantiomeric excess) was produced in a mild, cheap, and environment‐friendly process. This study demonstrates that L paracasei BD101 can be used as a biocatalyst to obtain chiral carbinol with excellent yield and selectivity. [ABSTRACT FROM AUTHOR]