Development and validation of a chiral UPLC-MS/MS method for quantifying S-Oxiracetam and R-Oxiracetam in human plasma, urine and feces: Application to a phase-I clinical pharmacokinetic study.

A chiral UPLC-MS/MS method was developed and validated to determine oxiracetam enantiomers in human plasma, urine, and feces. The R-Oxiracetam and S-Oxiracetam were quantified using a CHIRALPAK ®AD3 column at 25 â„ƒ, and the resolution was greater than 3.2. The S-Oxiracetam is the eutomer that isresponsible for the treatment of various brain damage. Isocratic elution was conducted at a flow rate of 0.9 mL/min for 6 min using the mixture of methanol and acetonitrile (methanol:acetonitrile, 15:85) containing 0.3‰ formic acid. The methods showed linearity at the range of 0.5-100 µg/mL for each oxiracetam enantiomer. A comprehensive validation process was carried out, covering aspects including linearity, selectivity, carryover, accuracy, precision, interferences, matrix effect, recovery, dilution integrity and stability in matrix and solution. The validated methods were successfully applied to quantifying R-Oxiracetam and S-Oxiracetam in human plasma, urine, and feces of 12 healthy subjects treated with either a single dose of 2 g S-Oxiracetam injection or 4 g Oxiracetam injection in a phase-I clinical trial. There was no significant difference for plasma pharmacokinetic parameters of S-Oxiracetam between the two regimens (P＞0.05). The S-Oxiracetam and Oxiracetam were primarily eliminated through urine in their original form, with cumulative excretion rates of 92.16% and 85.92%, respectively, within 24 h after administration. Enantiomers interconversion was not observed in the plasma, urine, or feces. The results of this study suggest that replacing 4 g Oxiracetam injection with 2 g S-Oxiracetam injection could offer clinical benefits by lowering the dosage and mitigating potential risks, based on the pharmacokinetic characteristics.

Enantioselective LC-MS/MS determination of antidepressants, ß-blockers and metabolites in agricultural soil, compost and digested sewage sludge.

In this work, an analytical method was optimised and validated for the simultaneous extraction and enantioselective determination of chiral ß-blockers, antidepressants and two of their metabolites in agricultural soils, compost and digested sludge. Sample treatment was based on ultrasound-assisted extraction and extract clean-up by dispersive solid-phase extraction. Analytical determination was carried out by liquid chromatography-tandem mass spectrometry using a chiral column. Enantiomeric resolutions were in the range from 0.71 to 1.36. Accuracy was in the range from 85 to 127% and precision, expressed as relative standard deviation, was lower than 17% for all the compounds. Method quantification limits were below 1.21-52.9 ng g-1 dry weight (dw) in soil, 0.76-35.8 ng g-1 dw in compost and 13.6-90.3 ng g-1 dw in digested sludge. Application to real samples revealed enantiomeric enrichment in the range especially in compost and digested sludge (enantiomeric fractions up to 1).

Development and validation of a chiral LC-MS/MS method for the separation and quantification of four synthetic cathinones in human whole blood and its application in stability analysis.

Synthetic cathinones, a subclass of new psychoactive substances, have gained high popularity on the recreational drugs market over the past years. These drugs typically have a chiral center, so they may exist as two stereoisomers. Therefore the pharmacological, pharmacokinetic or metabolic properties of their enantiomers are expected to differ. However, these drugs are often synthesized and sold as a racemic mixture, and as a consequence, differentiation of their (R)- and (S)- enantiomers is relevant in clinical and forensic toxicology. Information about single enantiomers of synthetic cathinones is relatively scarce due to challenges of their chiral analysis. Hence, a sensitive and reliable liquid chromatography-tandem mass spectrometry method was developed and validated for the chiral separation and quantification of four synthetic cathinones in human whole blood samples. The method was fully validated in terms of linearity, limit of detection, limit of quantification, bias, precision, carryover, interferences, matrix effects, recovery and processed sample stability and successfully applied to evaluate the stability as well as enantioselective degradation of synthetic cathinones enantiomers under various storage conditions. For most of the analytes, significant enantioselective degradation was observed when stored at room temperature or refrigerated, with the E2-enantiomers observed to more rapidly degrade under both conditions. This is the first report concerning the stability and enantioselective degradation of synthetic cathinone enantiomers in whole blood. Moreover, the inversion study demonstrated enantiomeric inversion of R-(-)- and S-(+)-methylenedioxypyrovalerone (MDPV) in human whole blood and methanolic solution.

Chiral LC-MS/MS method for the simultaneous determination of (R,S)-ketamine, (R,S)-norketamine, and (2R,6R;2S,6S)-hydroxynorketamine in mouse plasma and brain.

A convenient LC-MS/MS assay method to simultaneously and sensitively determine (R,S)-ketamine (Ket), (R,S)-norketamine (NK), and (2R,6R;2S,6S)-hydroxynorketamine (HNK) enantiomers in plasma and brain from mice was developed. This method enables the chiral separations of these six enantiomers in one analysis by constructing a column-switching system composed of one achiral column and two chiral columns with a relatively short analysis time (17 min). The chromatography involves the separation of (2R,6R;2S,6S)-HNK from (R,S)-Ket and (R,S)-NK on an octadecyl-silica column, followed by chiral separations on a CHIRALPAK AY-RH column for (2R,6R;2S,6S)-HNK or on a CHIRALPAK AS-RH column for the other analytes. The calibration curves for plasma and brain showed a good linearity in the range of 3-1000 ng/mL and 1.5-500 ng/g, respectively. The accuracy ranged from 90.0% to 104.0% in within-run and between-run. This validated method was applicable to determine the stereoselective pharmacokinetic profiles of (R,S)-Ket, (R,S)-NK, and (2R,6R;2S,6S)-HNK in plasma and brain collected from individual mice after a single intraperitoneal dosing of racemic Ket at an antidepressant dose. It is hoped that this assay will greatly help for understanding the relationship between the antidepressant actions of (R,S)-Ket enantiomers or their metabolites and their pharmacokinetics.

Cocaine adulteration with the anthelminthic tetramisole (levamisole/dexamisole): Long-term monitoring of its intake by chiral LC-MS/MS analysis of cocaine-positive hair samples.

Recent studies indicate that not only the anthelminthic levamisole but also the racemate tetramisole (R-/S-phenyltetraimidazothiazole, PTHIT) was found as an adulterant for cocaine. We herein report on the investigation of the prevalence of PTHIT among cocaine-positive hair samples and the discrimination of the presence of its stereoisomers levamisole and dexamisole. Cocaine-positive hair samples were collected in a forensic context in 2015 and mainly 2017 (n = 724). Cocaine and PTHIT concentrations have been determined by achiral liquid chromatography-tandem mass spectrometry (LC-MS/MS). For distinction of levamisole/dexamisole chiral LC-MS/MS was performed. Cocaine hair concentrations ranged from 500 (cut-off) to approximately 800 000 pg/mg. The study demonstrates a strong prevalence of PTHIT in cocaine users' hair (87%, n = 627). PTHIT hair concentrations ranged from below LLOQ 3.5 to approximately 61 000 pg/mg (median: 260 pg/mg). Surprisingly, enantiomeric ratios of levamisole/dexamisole ranged from 0.17 to 1.34 (median: 0.63). Therefore, PTHIT-adulterated street cocaine samples (n = 24) seized between 2013 and 2016 were tested. Samples mainly contained racemic tetramisole (87.5%), only one sample contained levamisole only and two samples contained non-racemic PTHIT. Our experiments suggest that the presence of tetramisole in biological samples may have hitherto been underestimated. Most probably higher dexamisole than levamisole concentrations in hair specimens arise from stereoselective metabolism and/or elimination. This is particularly important in light of the different pharmacological activities of the two enantiomers and potentially different adverse effects. Toxicological interpretations in intoxication cases with adulterated cocaine should not only consider levamisole but also tetramisole and terminology in scientific contributions should be used accordingly.

Simultaneous quantification of Schisandrin B enantiomers in rat plasma by chiral LC-MS/MS: Application in a stereoselective pharmacokinetic study.

Schisandrin B (Sch B) has received much attention owing to its various biological activities. Schisandrin B exists as a racemate in "wuweizi", a traditional Chinese medicine in China. In the present study, a novel chiral LC-MS/MS method was developed for enantioselective separation and determination of Schisandrin B in rat plasma. The plasma samples were prepared by liquid-liquid extraction (LLE). Schisandrol B was used as internal standard. Chiral separation was obtained on a Chiralpak IC column using 0.1% (v/v) formic acid in mixture of methanol and water (90:10, v/v) as a mobile phase. Parameters including the selectivity, linearity, precision, accuracy, extraction recovery, matrix effect and stability were evaluated. The method described here is simple and reproducible. The lower limit of quantification of 5.0 ng/mL for each Sch B enantiomer permits the use of the method in investigating the stereoselective pharmacokinetics of Sch B. Following racemic Sch B and "wuweizi" extracts, the area under the curve of (8R, 8'S)-Sch B was statistically higher than the one of (8S, 8' R)-Sch B, with a ratio of 1.16-1.40 in three cases. This study firstly reports the development and validation of enantioselective behavior of Sch B in vivo, and provides a reference for clinical practice and encourages further research into Sch B enantioselective metabolism and drug interactions.

Magnetic solid-phase extraction based on magnetic multiwalled carbon nanotubes for the simultaneous enantiomeric analysis of five ß-blockers in the environmental samples by chiral liquid chromatography coupled with tandem mass spectrometry.

In this work, the magnetic multiwalled carbon nanotubes (Mag-MWCNTs) were prepared by self-assembly method and characterized by scanning electron microscopy, X-ray powder diffraction, energy dispersive X-ray and vibrating sample magnetometer. Then, these synthetic Mag-MWCNTs were used as sorbents to extract five ß-blockers (atenolol, metoprolol, esmolol, pindolol and arotinolol) by magnetic solid-phase extraction. The target analytes adsorbed on Mag-MWCNTs were eluted and determined on a chiral α-acid glycoprotein column coupled with a triple quadrupole mass spectrometry. Eventually, the proposed method was applied to the analysis of the enantiomeric composition of the studied ß-blockers in three environmental samples, including river water, influent wastewater and effluent wastewater. Method detection and quantification limits for all enantiomers were in the range of 0.50-1.45 and 1.63-3.75ng/L, respectively. Satisfactory recovery (82.9-95.6%), good intra-day precision (RSD 0.4-10.4%) and inter-day precision (RSD 2.9-7.4%) were also obtained. With numerous advantages such as simplicity of operation, rapidity and high enrichment factor, the newly developed method has potential to assess the enantioselectivity of chiral drugs in ecotoxicity and biodegradation processes, which is also a new expanded application of Mag-MWCNTs in the environmental analysis.

A study of the origin of chloramphenicol isomers in honey.

Due to the unexpected detection of chloramphenicol isomer residues in honey, we have studied the hypothesis of unauthorized or unintended use of unregistered veterinary drug preparations. First, we have investigated honey samples in which a discrepancy was observed between the results of the immunological screening methods and the confirmatory liquid chromatography-tandem mass spectrometry (LC-MS/MS) method. In all samples, previously identified to be contaminated with the banned antibiotic chloramphenicol according to LC-MS/MS only, the presence of dextramycin (SS-para isomer of chloramphenicol) was detected by chiral LC-MS/MS. The source of dextramycin in honey was investigated by studying the preparations utilized in apiaries from which the above non-compliant honey samples have been received. In all these preparations (beehive strips applied against the mite Varroa destructor) chloramphenicol was detected in the concentrations ranging from 33 to 34,400 µg kg-1 . Chiral LC-MS/MS demonstrated the presence of chloramphenicol and dextramycin in different ratios, and it was concluded that these preparations can be the source of chloramphenicol and dextramycin residues in honey. These preparations were of foreign production and are not officially registered in accordance with current legislation.

A rapid and sensitive chiral LC-MS/MS method for the determination of ketamine and norketamine in mouse plasma, brain and cerebrospinal fluid applicable to the stereoselective pharmacokinetic study of ketamine.

A novel method for the rapid and sensitive chiral determination of ketamine and norketamine in mouse plasma, brain and cerebrospinal fluid (CSF) was developed using liquid chromatography-tandem mass spectrometry (LC-MS/MS). This method reduces the required matrix volume, compared with a previously reported chiral assay method for ketamine and norketamine. The method involves the deproteinization of a small amount of biological matrix (corresponding to 5µL of plasma, 10mg of brain, or 2.5µL of CSF) using a water-miscible organic solvent containing 2H4-norketamine as an internal standard, the direct injection of the organic supernatant into an LC-MS/MS system, chiral separation on a CHIRALPAK AS-3R column (4.6mm i.d.×100mm, 3µm particles), and detection by electrospray ionization-selected reaction monitoring with an analytical run time of 5min. The lower limits of quantification for ketamine and norketamine enantiomers were 1ng/mL (plasma), 0.5ng/g (brain) and 2ng/mL (CSF). A good linearity of the calibration curves was obtained within a range of 1000-fold. The newly developed method was successfully used to determine the concentrations of ketamine and norketamine in mouse samples (plasma, brain and CSF) in a stereoselective manner. Therefore, this method is expected to contribute to the elucidation of the roles of ketamine and its metabolites in the antidepressant actions of ketamine.

A chiral LC-MS/MS method for the enantioselective determination of R-(+)- and S-(-)-pantoprazole in human plasma and its application to a pharmacokinetic study of S-(-)-pantoprazole sodium injection.

Pantoprazole, a proton pump inhibitor, is clinically used for the treatment of peptic diseases. An enantioselective LC-MS/MS method was developed and validated for the simultaneous determination of pantoprazole enantiomers in human plasma. Pantoprazole enantiomers and the internal standard were extracted from plasma using acetonitrile. Chiral separation was carried on a Chiralpak IE column using the mobile phase consisted of 10 mm ammonium acetate solution containing 0.1% acetic acid-acetonitrile (28 : 72, v/v). MS analysis was performed on an API 4000 mass spectrometer. Multiple reactions monitoring transitions of m/z 384.1→200.1 and 390.1→206.0 were used to quantify pantoprazole enantiomers and internal standard, respectively. For each enantiomer, no apparent matrix effect was found, the calibration curve was linear over 5.00-10,000 ng/mL, the intra- and inter-day precisions were below 10.0%, and the accuracy was within the range of -5.6% to 0.6%. This method was applied to the stereoselective pharmacokinetic studies in human after intravenous administration of S-(-)-pantoprazole sodium injections. No chiral inversion was observed during sample storage, preparation procedure and analysis. While R-(+)-pantoprazole was detected in human plasma with a slightly high concentration, which implied that S-(-)-pantoprazole may convert to R-(+)-pantoprazole in some subjects.

Enantioselective analysis of chloramphenicol residues in honey samples by chiral LC-MS/MS and results of a honey survey.

Chloramphenicol (CAP) is a broad-spectrum antibiotic used widely in both human and veterinary medication. Since 1994, CAP has not been authorised for use in food-producing animals in the European Union due to several adverse effects. A minimum required performance level (MRPL) of 0.3 µg kg-1 was established in 2003. The CAP molecule contains two asymmetric centres, thus in total four para-CAP stereoisomers exist. Only the RR-CAP enantiomer is bioactive, having significant antimicrobial activity. For the first time a chiral LC-MS/MS method is reported to identify and quantify the four CAP enantiomers at residue levels in honey samples. The method was validated at two concentration levels. The decision limits (CCα) and detection capabilities (CCß) were well below 0.3 µg kg-1, with limits of quantification (LOQs) between 0.08 and 0.12 µg kg-1 for all four enantiomers. The method provides a sensitive and reliable analysis of CAP enantiomers in honey, and proved its robustness during the daily routine analyses of numerous honey samples. In an internal honey survey, in total 40 honey samples from different geographical regions with identified CAP residues at or above the MRPL were reanalysed by chiral LC-MS/MS. In nine honey samples only the bioactive RR-CAP was detected as anticipated. However, in all other 31 honey samples the non-bioactive SS-CAP was also identified and quantified unambiguously. In 10 of these samples, mixtures of RR- and SS-CAP were analysed, and in 21 samples only the SS-CAP enantiomer, with concentrations up to 2.2 µg kg-1. Most of these samples are honeys from Ukraine and Eastern Europe. This is the first report of SS-CAP residues in food samples. The potential sources for these findings are discussed and the need of further systematic studies emphasised. It is recommended to examine in more depth the toxicological profile of the individual CAP stereoisomers.

Enantioselective analysis of citalopram and demethylcitalopram in human whole blood by chiral LC-MS/MS and application in forensic cases.

Citalopram is one of the most frequently used antidepressants in Denmark. It is marketed as a racemic mixture (50:50) of S- and R-enantiomers as well as of the S-enantiomer alone, which is the active enantiomer named escitalopram that processes the inhibitory effects. In this study, a chiral liquid chromatography-tandem mass spectrometry (LC-MS/MS) method is developed for the measurement of citalopram and demethylcitalopram enantiomers in whole blood and is applied to forensic cases. Whole blood samples (0.10 g) were extracted with butyl acetate after adjusting the pH with 2 M NaOH. The analytes were separated on a 250 × 4.6 mm Chirobiotic V, 5 µm column by isocratic elution with methanol:ammonia:acetic acid (1000:1:1) using an ultra-high-pressure liquid chromatography (UHPLC) system. Quantification was performed by tandem mass spectrometry (MS/MS) using multiple reaction monitoring (MRM) in the positive mode. The total chromatographic run time was 20 min. The limit of detection (LOD) and quantification (LOQ) were 0.001 and 0.005 mg/kg of all four enantiomers, respectively. Linear behaviour was obtained for all four enantiomers from LOQ to 0.50 mg/kg blood with absolute recoveries from 71 to 80%. The method showed an acceptable precision and accuracy as the obtained coefficient of variation, and bias values were ≤16% for all enantiomers. After the validation of the method, a correlation with the racemic method was assessed and found to be acceptable. Then, the method was successfully applied to authentic blood samples from forensic investigations demonstrating that escitalopram was less frequent than citalopram among all forensic cases. Copyright © 2017 John Wiley & Sons, Ltd.

Distinction of clenbuterol intake from drug or contaminated food of animal origin in a controlled administration trial - the potential of enantiomeric separation for doping control analysis.

The differentiation of clenbuterol abuse and unintentional ingestion from contaminated meat is crucial with respect to the valuation of an adverse analytical finding in human sports doping control. The proportion of the two enantiomers of clenbuterol may serve as potential discriminating parameter. For the determination of the individual enantiomers, specific methods were developed and validated for the different matrices under investigation based on chiral chromatography coupled to tandem mass spectrometry. Data are presented from the administration to humans of clenbuterol from a pharmaceutical preparation, and from cattle meat and liver containing residues. A shift in the proportion of the enantiomers in cattle meat is detected and this signature is also found in human urine after ingestion. Thus, an altered enantiomeric composition of clenbuterol may be used to substantiate athletes' claims following adverse analytical findings in doping control. However, in meat, the enantiomeric composition was found to be highly variable. Species as well as tissue dependent variances need to be considered in interpreting enantiomer discrimination. Analysis of post administration urines from a controlled experiment comparing the administration of racemic clenbuterol from a registered pharmaceutical preparation and the administration of residue-containing meat and liver (nonracemic mixture) from treated animals is reported. Furthermore doping control samples from Mexican U17 World Championship 2011 of the Fédération Internationale de Football Association (FIFA), with adverse analytical findings for clenbuterol, were re-analysed.

Solid-phase extraction combined with dispersive liquid-liquid microextraction and chiral liquid chromatography-tandem mass spectrometry for the simultaneous enantioselective determination of representative proton-pump inhibitors in water samples.

This report describes, for the first time, the simultaneous enantioselective determination of proton-pump inhibitors (PPIs-omeprazole, lansoprazole, pantoprazole, and rabeprazole) in environmental water matrices based on solid-phase extraction combined with dispersive liquid-liquid microextraction (SPE-DLLME) and chiral liquid chromatography-tandem mass spectrometry. The optimized results of SPE-DLLME were obtained with PEP-2 column using methanol-acetonitrile (1/1, v/v) as elution solvent, dichloroethane, and acetonitrile as extractant and disperser solvent, respectively. The separation and determination were performed using reversed-phase chromatography on a cellulose chiral stationary phase, a Chiralpak IC (250 mm × 4.6 mm, 5 µm) column, under isocratic conditions at 0.6 mL min(-1) flow rate. The analytes were detected in multiple reaction monitoring (MRM) mode by triple quadrupole mass spectrometry. Isotopically labeled internal standards were used to compensate matrix interferences. The method provided enrichment factors of around 500. Under optimal conditions, the mean recoveries for all eight enantiomers from the water samples were 89.3-107.3 % with 0.9-10.3 % intra-day RSD and 2.3-8.1 % inter-day RSD at 20 and 100 ng L(-1) levels. Correlation coefficients (r (2)) ≥ 0.999 were achieved for all enantiomers within the range of 2-500 µg L(-1). The method detection and quantification limits were at very low levels, within the range of 0.67-2.29 ng L(-1) and 2.54-8.68 ng L(-1), respectively. This method was successfully applied to the determination of the concentrations and enantiomeric fractions of the targeted analytes in wastewater and river water, making it applicable to the assessment of the enantiomeric fate of PPIs in the environment. Graphical Abstract Simultaneous enantioselective determination of representative proton-pump inhibitors in water samples.

Qualitative analysis and enantiospecific determination of angular-type pyranocoumarins in Peucedani Radix using achiral and chiral liquid chromatography coupled with tandem mass spectrometry.

Angular-type pyranocoumarins (APs), the derivatives of khellactone, are widely documented as the main active constituents in Peucedani Radix (Chinese name: Qian-hu). Owing to the natural occurrence of chiral centers, enantiomers of APs are extensively distributed in the original plant, and enantioselective performances have been definitely demonstrated for these enantiomers. In current study, the chemical characterization of the major and minor APs in Peucedani Radix was performed using ultra high performance liquid chromatography coupled with diode array detector and hybrid ion trap-orbitrap mass spectrometry. On the other hand, a heart-cut two-dimensional achiral-chiral liquid chromatography combining triple quadropole-linear ion trap mass spectrometry system (2D LC-MS/MS) was developed for simultaneous enantiospecific quantification of eighteen coumarins, including seven pairs of enantiomers. Eleven APs (1-11) were recruited to propose UV absorption characteristics and electrospray ionization fragmentation patterns of APs. A total of 42 components were categorized into APs based on their UV spectral properties and identified according to the proposed mass fragmentation pathways, while two linear-type furanocoumarins (12-13) were unambiguously assigned by further purification. A Capcell core RP-C18 column was employed in the primary LC dimension to achieve efficient racemic separation for the main chemical constituents (1-9 and 12-13) in Peucedani Radix, while a Chiralpak AD-RH column was utilized in the secondary dimension to contribute enantioselective separation for seven enantiomerically enriched components (1, 3 and 5-9). Collectively, the results provided the chemical evidences for revealing the material basis of the therapeutic effects of Peucedani Radix, and the developed 2D LC-MS/MS system in the present study is expected to be an ideal tool for the quality control of Peucedani Radix as well as a reliable technique for complex matrices containing both achiral and chiral components.

Simultaneously enantiospecific determination of (+)-trans-khellactone, (+/-)-praeruptorin A, (+/-)-praeruptorin B, (+)-praeruptorin E, and their metabolites, (+/-)-cis-khellactone, in rat plasma using online solid phase extraction-chiral LC-MS/MS.

Many chiral drugs are used as the racemic mixtures in clinical practice. The occurrence of enantioselectively pharmacological activities calls for the development of enantiospecific analytical approaches during pharmacokinetic studies of enantiomers. Sample preparation plays a key role during quantitative analysis of biological samples. In current study, a rapid and reliable online solid phase extraction-chiral high performance liquid chromatography-tandem mass spectrometry (online SPE-chiral LC-MS/MS) method was developed for the simultaneously enantiospecific quantitation of (+)-trans-khellactone (dTK), (+/-)-cis-khellactone (d/lCK), (+/-)-praeruptorin A (d/lPA), (+/-)-praeruptorin B (d/lPB) and (+)-praeruptorin E (dPE), the main active angular-type pyranocoumarins (APs) in Peucedani Radix (Chinese name: Qian-hu) or the major metabolites of those APs, in rat plasma. The validation assay results described here show good selectivity and enantiospecificity, extraction efficiency, accuracy and precision with quantification limits (LOQs) of 2.57, 1.28, 1.28, 1.88, 4.16, 4.16 and 4.18ngmL(-1) for dTK, lCK, dCK, dPA, dPB, lPB and dPE, respectively, while lPA was not detected in rat plasma due to the carboxylesterase(s)-mediated hydrolysis. In addition, the validated system was satisfactorily applied to characterize the pharmacokinetic properties of those components in normal and chronic obstructive pulmonary disease (COPD) rats following oral administration of Qian-hu extract. dCK and lCK were observed as the main herb-related compounds in plasma. Enantioselectively pharmacokinetic profiles occurred for dCK vs lCK, dPA vs lPA, and dPB vs lPB in either normal or COPD rats. The proposed whole system is expected to be a preferable analytical tool for in vivo study of chiral drugs, in particular for the characterization of enantioselectively pharmacokinetic profiles.