Analysis of carvedilol enantiomers in human plasma using chiral stationary phase column and liquid chromatography with tandem mass spectrometry

Carvedilol is an antihypertensive drug available as a racemic mixture. (?)‐(S)‐carvedilol is responsible for the nonselective β‐blocker activity but both enantiomers present similar activity on α₁‐adrenergic receptor. To our knowledge, this is the first study of carvedilol enantiomers in human plasma using a chiral stationary phase column and liquid chromatography with tandem mass spectrometry. The method involves plasma extraction with diisopropyl ether using metoprolol as internal standard and direct separation of the carvedilol enantiomers on a Chirobiotic T® (Teicoplanin) column. Protonated ions [M + H]⁺ and their respective ion products were monitored at transitions of 407 > 100 for the carvedilol enantiomers and 268 > 116 for the internal standard. The quantification limit was 0.2 ng ml^?1 for both enantiomers in plasma. The method was applied to study enantioselectivity in the pharmacokinetics of carvedilol administered as a single dose of 25 mg to a hypertensive patient. The results showed a higher plasma concentration of (+)‐(R)‐carvedilol (AUC^0–∞ 205.52 vs. 82.61 (ng h) ml^?1), with an enantiomer ratio of 2.48. Chirality, 2012. © 2012 Wiley Periodicals, Inc.     

Ultra‐performance convergence chromatography with tandem mass spectrometry‐assisted method for rapid enantioseparation and determination of fluazifop‐butyl in tobacco and soil

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.     

Enantioseparation and Determination of the Chiral Fungicide Furametpyr Enantiomers in Rice,Soil, and Water by High‐Performance Liquid Chromatography

The chiral fungicide furametpyr is widely used in the rice field to control rice sheath blight; however, furametpyr enantiomers are treated as just one compound in traditional achiral analysis, which gives only partial information. An effective chiral analytical method was developed for the resolution and determination of the fungicide furametpyr enantiomers in rice, soil, and water samples. Furametpyr enantiomers were excellently separated and determined on a Chiralpak AD‐H column with n‐hexane/ethanol (90:10, v/v) as mobile phase at a flow rate of 0.8 mL min^‐1 with UV detection at 220 nm. The resolution was up to 8.85. The first eluted enantiomer was (+)‐furametpyr and the second eluted one was (?)‐furametpyr. The effects of mobile‐phase composition and column temperature on the enantioseparation were evaluated. The method was validated for linearity, repeatability, accuracy, limit of detection (LOD), and limit of quantification LOQ. LOD was 2.0 µg kg^‐1 in water, 0.02 mg kg^‐1 in soil, and 0.07 mg kg^‐1 in rice with an LOQ of 6.7 µg kg^‐1 in water, 0.07 mg kg^‐1 in soil, and 0.23 mg kg^‐1 in rice. The average recoveries of the pesticide in all matrices ranged from 73.1 to 101.8% for all fortification levels. The precision values associated with the analytical method, expressed as relative standard deviation (RSD) values, were below 14.0% in all matrices. The methodology was successfully applied for the enantioselective analysis of furametpyr enantiomers in real samples. Chirality 25:904–909, 2013. © 2013 Wiley Periodicals, Inc.     

Enantioselective LC-MS/MS method for the determination of cloperastine enantiomers in rat plasma and its pharmacokinetic application

Cloperastine is a central antitussive used to reduce the frequency and intensity of coughing on a short-term basis. In this study, a reliable chiral LC-MS/MS technology has been developed for the quantification of cloperastine enantiomers in the rat plasma. Carbinoxamine was selected as the internal standard. The enantioseparation of cloperastine was performed on a Chiralpak IA column with a mobile phase composed of acetonitrile-water-ammonium hydroxide (80:20:0.1, v/v/v) at a flow rate of 0.6 mL/min. Cloperastine enantiomers were detected by mass spectrometry in multiple reaction monitoring mode with a positive electrospray ionization source. The method was validated over the linear concentration range of 0.05 to 10.0 ng/mL (5.0 × 10⁻⁴ ng to 0.10 ng) for both enantiomers. The lower limit of quantification (LLOQ) for each analyte was determined as 0.05 ng/mL. The relative standard deviations (RSDs) of intraday and interday precision was less than 13.9%, and the relative error (RE) of accuracy ranged from −5.4% to 6.1%, which were within the acceptance criteria. Finally, an application to the stereoselective pharmacokinetics of cloperastine in rats was successfully realized in our assay. The developed method on a commercially available Chiralpak IA column under isocratic mobile phase is advantageous to analyze cloperastine enantiomers in plasma samples collected for enantioselective metabolism or drug interaction studies.     

Analysis of flumequine enantiomers in rat plasma by UFLC‐ESI‐MS/MS

In this study the analysis and confirmation of flumequine enantiomers in rat plasma by ultra‐fast liquid chromatography coupled with electron spray ionization mass spectrometry (using propranolol as an internal standard [IS]) was developed and validated. Plasma samples were prepared by liquid–liquid extraction using methyl tert‐butyl ether as the extraction solvent. Direct resolution of the R‐ and S‐isomers was performed on a CHIRALCEL OJ‐RH column (4.6 × 150 mm, 5 μm) using acetonitrile / 0.1% formic acid / 1 mM ammonium acetate as the mobile phase. Detection was operated by electron spray ionization in the selected ion monitoring and positive ion mode. The target ions at m/z 262.1 and m/z 260.1 were selected for the quantification of the enantiomers and IS, respectively. The linear range was 0.5–500 ng/mL. The precisions (coefficient of variation, CV%) and recoveries were 1.43–8.68 and 94.24–106.76%, respectively. The lowest quantitation limit for both enantiomers is 0.5 ng/mL, which is sensitive enough to be applied to sample analysis in other related studies.     

Electrochromatographic enantioseparation of amino acids using polybutylmethacrylate-based chiral monolithic column by capillary electrochromatography

This article describes the development of a polybutylmethacrylate‐based monolithic capillary column as a chiral stationary phase. The chiral monolithic column was prepared by polymerization of butyl methacrylate (BMA), ethylene dimethacrylate (EDMA), and N‐methacryloyl‐l ‐glutamic acid (MAGA) in the presence of porogens. The porogen mixture included N,N‐dimethyl formamide and phosphate buffer. MAGA was used as a chiral selector. The effect of MAGA content was investigated on electrochromatographic enantioseparation of d,l ‐histidine, d,l ‐tyrosine, d,l ‐phenyl alanine, and d,l ‐glutamic acid. The effect of acetonitrile (ACN) content in mobile phase on electro‐osmotic flow was also investigated. It was demonstrated that the poly(BMA‐EDMA‐MAGA) monolithic chiral column can be used for the electrochromatographic enantioseparation of amino acids by capillary electrochromatography (CEC). The mobile phase was ACN/10 mM phosphate buffer (45:55%) adjusted to pH 2.7. It was observed that l ‐enantiomers of the amino acids migrated before d ‐enantiomers. The separation mechanism of electrochromatographic enantioseparation of amino acids in CEC is discussed. Chirality 24:606–609, 2012. © 2012 Wiley Periodicals, Inc.     

A 3D Homochiral MOF [Cd2(d‐cam)3]•2Hdma•4dma for HPLC Chromatographic Enantioseparation

Up to now, some chiral metal‐organic frameworks (MOFs) have been reported for enantioseparation in liquid chromatography. Here we report a homochiral MOF, [Cd2(d‐cam)3]·2Hdma·4dma, used as a new chiral stationary phase for high‐performance liquid chromatographic enantioseparation. Nine racemates of alcohol, naphthol, ketone, and base compounds were used as analytes for evaluating the separation properties of the chiral MOF packed column. Moreover, some effects such as mobile phase composition, column temperature, and analytes mass for separations on this chiral column also were investigated. The relative standard deviations for the resolution values of run‐to‐run and column‐to‐column were less than 2.1% and 3.2%, respectively. The experimental results indicate that the homochiral MOF offered good recognition ability, which promotes the application of chiral MOFs use as stationary phase for enantioseparation. Chirality 28:340–346, 2016. © 2016 Wiley Periodicals, Inc.     

Validation of a Chiral Liquid Chromatographic Method for the Degradation Behavior of Flumequine Enantiomers in Mariculture Pond Water

In this work, flumequine (FLU) enantiomers were separated using a Chiralpak OD‐H column, with n‐hexane‐ethanol (20:80, v/v) as the mobile phase at a flow rate of 0.6 mL/min. Solid phase extraction (SPE) was used for cleanup and enrichment. The limit of detection, limit of quantitation, linearity, precision, and intra/interday variation of the chiral high‐performance liquid chromatography (HPLC) method were determined. The developed method was then applied to investigate the degradation behavior of FLU enantiomers in mariculture pond water samples. The results showed that the degradation of FLU enantiomers under natural, sterile, or dark conditions was not enantioselective. Chirality 28:649–655, 2016. © 2016 Wiley Periodicals, Inc.     

Analysis of Oxcarbazepine and the 10‐Hydroxycarbazepine Enantiomers in Plasma by LC‐MS/MS: Application in a Pharmacokinetic Study

Oxcarbazepine is a second‐generation antiepileptic drug indicated as monotherapy or adjunctive therapy in the treatment of partial seizures or generalized tonic–clonic seizures in adults and children. It undergoes rapid presystemic reduction with formation of the active metabolite 10‐hydroxycarbazepine (MHD), which has a chiral center at position 10, with the enantiomers (S)‐(+)‐ and R‐(?)‐MHD showing similar antiepileptic effects. This study presents the development and validation of a method of sequential analysis of oxcarbazepine and MHD enantiomers in plasma using liquid chromatography with tandem mass spectrometry (LC‐MS/MS). Aliquots of 100 μL of plasma were extracted with a mixture of methyl tert‐butyl ether: dichloromethane (2:1). The separation of oxcarbazepine and the MHD enantiomers was obtained on a chiral phase Chiralcel OD‐H column, using a mixture of hexane:ethanol:isopropanol (80:15:5, v/v/v) as mobile phase at a flow rate of 1.3 mL/min with a split ratio of 1:5, and quantification was performed by LC‐MS/MS. The limit of quantification was 12.5 ng oxcarbazepine and 31.25 ng of each MHD enantiomer/mL of plasma. The method was applied in the study of kinetic disposition of oxcarbazepine and the MHD enantiomers in the steady state after oral administration of 300 mg/12 h oxcarbazepine in a healthy volunteer. The maximum plasma concentration of oxcarbazepine was 1.2 µg/mL at 0.75 h. The kinetic disposition of MHD is enantioselective, with a higher proportion of the S‐(+)‐MHD enantiomer compared to R‐(?)‐MHD and an AUC^0‐12 _{S‐(+)/R‐(?)} ratio of 5.44. Chirality 25:897–903, 2013. © 2013 Wiley Periodicals, Inc.     

Enantioselective analysis of ibuprofen enantiomers in mice plasma and tissues by high‐performance liquid chromatography with fluorescence detection: Application to a pharmacokinetic study

A direct fluorometric high‐performance liquid chromatography (HPLC) method was developed and validated for the analysis of ibuprofen enantiomers in mouse plasma (100 μl) and tissues (brain, liver, kidneys) using liquid–liquid extraction and 4‐tertbutylphenoxyacetic acid as an internal standard. Separation of enantiomers was accomplished in a Chiracel OJ‐H chiral column based on cellulose tris(4‐methylbenzoate) coated on 5 μm silica‐gel, 250 x 4.6 mm at 22 °C with a mobile phase composed of n‐hexane, 2‐propanol, and trifluoroacetic acid that were delivered in gradient elution at a flow rate of 1 ml min⁻¹. A fluorometric detector was set at: λ_excit. = 220 nm and λ_emis. = 290 nm. Method validation included the evaluation of the selectivity, linearity, lower limit of quantification (LLOQ), within‐run and between‐run precision and accuracy. The LLOQ for the two enantiomers was 0.125 μg ml⁻¹ in plasma, 0.09 μg g⁻¹ in brain, and 0.25 μg g⁻¹ in for liver and kidney homogenates. The calibration curves showed good linearity in the ranges of each enantiomers: from 0.125 to 35 μg ml⁻¹ for plasma, 0.09–1.44 μg g⁻¹ for brain, and 0.25–20 μg g⁻¹ for liver and kidney homogenates. The method was successfully applied to a pharmacokinetic study of ibuprofen enantiomers in mice treated i.v. with 10 mg kg⁻¹ of racemate.     

High‐Throughput Chiral LC–MS/MS Method Using Overlapping Injection Mode for the Determination of Pantoprazole Enantiomers in Human Plasma with Application to Pharmacokinetic Study

A sensitive and high‐throughput chiral liquid chromatography–tandem mass spectrometry method was developed and validated for the quantification of R‐pantoprazole and S‐pantoprazole in human plasma. Sample extraction was carried out by using ethyl acetate liquid–liquid extraction in 96‐well plate format. The separation of pantoprazole enantiomers was performed on a CHIRALCEL OJ‐RH column and an overlapping injection mode was used to achieve a run time of 5.0 min/sample. The mobile phase consisted of 1) 10 mM ammonium acetate in methanol: acetonitrile (1:1, v/v) and 2) 20 mM ammonium acetate in water. Isocratic elution was used with flow rate at 500 μL/min. The enantiomers were quantified on a triple‐quadrupole mass spectrometer under multiple reaction monitoring (MRM) mode with m/z 382.1/230.0 for pantoprazole and m/z 388.4/230.1 for pantoprazole‐d7. Linearity from 20.0 to 5000 ng/mL was established for each enantiomer (r² > 0.99). Extraction recovery ranged from 91.7% to 96.4% for R‐pantoprazole and from 92.5% to 96.5% for S‐pantoprazole and the IS‐normalized matrix factor was 0.98 to 1.07 for R‐pantoprazole and S‐pantoprazole, respectively. The method was demonstrated with acceptable accuracy, precision, selectivity, and stability and the method was applied to support a pharmacokinetic study of a phase I clinical trial of racemic pantoprazole in healthy Chinese subjects. Chirality 28:569–575, 2016. © 2016 Wiley Periodicals, Inc.     

Preparation and characterization of a new open‐tubular capillary column for enantioseparation by capillary electrochromatography

In order to use the enantioseparation capability of cationic cyclodextrin and to combine the advantages of capillary electrochromatography (CEC) with open‐tubular (OT) column, in this study, a new OT‐CEC, coated with cationic cyclodextrin (1‐allylimidazolium‐β‐cyclodextrin [AI‐β‐CD]) as chiral stationary phase (CSP), was prepared and applied for enantioseparation. Synthesized AI‐β‐CD was characterized by infrared (IR) spectrometry and mass spectrometry (MS). The preparation conditions for the AI‐β‐CD‐coated column were optimized with the orthogonal experiment design L₉(3⁴). The column prepared was characterized by scanning electron microscopy (SEM) and elemental analysis (EA). The results showed that the thickness of stationary phase in the inner surface of the AI‐β‐CD‐coated columns was about 0.2 to 0.5 μm. The AI‐β‐CD content in stationary phase based on the EA was approximately 2.77 mmol·m^?2. The AI‐β‐CD‐coated columns could separate all 14 chiral compounds (histidine, lysine, arginine, glutamate, aspartic acid, cysteine, serine, valine, isoleucine, phenylalanine, salbutamol, atenolol, ibuprofen, and napropamide) successfully in the study and exhibit excellent reproducibility and stability. We propose that the column, coated with AI‐β‐CD, has a great potential for enantioseparation in OT‐CEC.     

Determination of bevantolol enantiomers in human plasma by coupled achiral-chiral high performance-liquid chromatography

A coupled achiral-chiral high performance liquid chromatographic method was developed and fully validated for the determination of bevantolol enantiomers, (-)-(S)-bevantolol and (+)-(R)-bevantolol, in human plasma. Plasma samples were prepared by solid phase extraction with Sep-Pak Plus C18 cartridges followed by HPLC. Bevantolol enantiomers and (+)-(R)-Propranolol as internal standard (IS) were preseparated from interfering components in plasma on a Phenomenex silica column and bevantolol enantiomers and IS were resolved and determined on a Chiralcel OJ-H chiral stationary phase. The two columns were connected by a switching valve equipped with silica precolumn. The Precolumn was used to concentrate bevantolol in the eluent from the achiral column before back flushing onto chiral phase. A detailed validation of the method was performed accordingly to FDA guidelines. For each enantiomer the assay was linear between 20 and 1600 ng/ml. The quantification limits of both bevantolol enantiomers were 20 ng/ml. The intraday variation was between 1.07 and 12.64% in relation to the measured concentration and the interday variation was 0.91 and 11.79%. The method has been applied to the determination of (-)-(S)- and (+)-(R)-bevantolol in plasma from healthy volunteers dosed with racemic bevantolol hydrochloride.     

Determination of terbutaline enantiomers in human urine by coupled achiral–chiral high-performance liquid chromatography with fluorescence detection

A coupled achiral–chiral high-performance liquid chromatographic system with fluorescence detection at excitation/emission wavelengths of 276/306 nm has been developed for the determination of the enantiomers of terbutaline, (S)-(+)-terbutaline and (R)-(−)-terbutaline in urine. Urine samples were prepared by solid-phase extraction with Sep-pak silica, followed by HPLC. The terbutaline was preseparated from the interfering components in urine on Phenomenex silica column and the terbutaline enantiomers and betaxolol were resolved and determined on a Sumichiral OA-4900 chiral stationary phase. The two columns were connected by a switching valve equipped with silica precolumn. The precolumn was used to concentrate the terbutaline in the eluent from the achiral column before back flushing onto the chiral phase. For each enantiomer the assay was linear between 1 and 250 ng/ml (R²=0.9999) and the detection limit was 0.3 ng/ml. The intra-day variation was between 4.6 and 11.6% in relation to the measured concentration and the inter-day variation was 4.3–11.0%. It has been applied to the determination of (S)-(+)-terbutaline and (R)-(−)-terbutaline in urine from a healthy volunteer dosed with racemic terbutaline sulfate.     

Simultaneous analysis of lignocaine and bupivacaine enantiomers in plasma by high-performance liquid chromatography

A sensitive analytical procedure is described for the simultaneous determination of lignocaine and the enantiomers of bupivacaine in biological fluids using diazepam as an internal standard. After solvent extraction into hexane, the local anaesthetics were separated using an α₁-acid glycoprotein (AGP) column and detected at 214 nm. Calibration curves were linear (r²>0.99) in the concentration range of 5 to 500 ng/ml for the enantiomers of bupivacaine and 12.5 to 1000 ng/ml for lignocaine. The corresponding limits of detection were 4 ng/ml and 10 ng/ml, respectively. The method was applied to the analysis of plasma from a healthy woman undergoing tubal ligation.     

Chiral analysis of ammuxetine enantiomers in dog plasma using online SPE/liquid chromatography with tandem mass spectrometric detection after precolumn chiral derivatization

Ammuxetine (AMT), a novel chiral antidepressant candidate compound, exhibits better antidepression effects than duloxetine in different animal models. In this article, a chiral derivatization method, combined with online solid phase extraction (online SPE) and liquid chromatography–tandem mass spectrometry (LC–MS/MS), was developed for the chiral separation of AMT enantiomers after administration of racemic AMT to dogs. The derivatization reaction employed 2,3,4,6‐tetra‐O‐acetyl‐b‐glucopyr‐anosyl isothiocyanate (GITC) as a precolumn chiral derivatization reagent. A SPE column Retain PEP Javelin (10 × 2.1 mm) was used to remove proteins and other impurities in plasma samples. The enantiomeric derivatives were separated on a ZORBAX SB‐C₁₈ column (50 × 2.1 mm × 3.5 μm) with an isocratic elution procedure. The selected multiple reaction monitoring mode of the positive ion was performed and the parent to the product transitions m/z 681.0/543.1 and m/z 687.4/543.1 were used to measure the derivatives of AMT and duloxetine (internal standard) with electrospray ionization. The method was validated in terms of specificity, linearity, sensitivity, precision, accuracy, matrix effect, and stability. The method was applied to a pharmacokinetics study of AMT racemate in dogs. The results suggested that the pharmacokinetic of AMT enantiomers might be stereoselective in dogs.     

A New Chiral Residue Analysis Method for Triazole Fungicides in Water Using Dispersive Liquid‐Liquid Microextraction (DLLME)

A rapid, simple, reliable, and environment‐friendly method for the residue analysis of the enantiomers of four chiral fungicides including hexaconazole, triadimefon, tebuconazole, and penconazole in water samples was developed by dispersive liquid–liquid microextraction (DLLME) pretreatment followed by chiral high‐performance liquid chromatography (HPLC)‐DAD detection. The enantiomers were separated on a Chiralpak IC column by HPLC applying n‐hexane or petroleum ether as mobile phase and ethanol or isopropanol as modifier. The influences of mobile phase composition and temperature on the resolution were investigated and most of the enantiomers could be completely separated in 20 min under optimized conditions. The thermodynamic parameters indicated that the separation was enthalpy‐driven. The elution orders were detected by both circular dichroism detector (CD) and optical rotatory dispersion detector (ORD). Parameters affecting the DLLME performance for pretreatment of the chiral fungicides residue in water samples, such as the extraction and dispersive solvents and their volume, were studied and optimized. Under the optimum microextraction condition the enrichment factors were over 121 and the linearities were 30–1500 µg L^?1 with the correlation coefficients (R²) over 0.9988 and the recoveries were between 88.7% and 103.7% at the spiking levels of 0.5, 0.25, and 0.05 mg L^?1(for each enantiomer) with relative standard deviations varying from 1.38% to 6.70% (n = 6) The limits of detection (LODs) ranged from 8.5 to 29.0 µg L^?1(S/N = 3). Chirality 25:567‐574, 2013. © 2013 Wiley Periodicals, Inc.     

Chiral separation and determination of amino acid enantiomers in fruit juice by open‐tubular nano liquid chromatography

A novel chiral porous‐layer stationary phase was developed for use in open‐tubular nano liquid chromatography. The stationary phase was prepared by an in‐situ polymerization of 3‐chloro‐2‐hydroxypropylmethacrylate (HPMA‐Cl) and ethylene dimethacrylate (EDMA). The reactive chloro groups at the surface of the porous stationary phase were reacted with β‐Cyclodextrin (β‐CD). The resulting morphology was characterized by using scanning electron microscopy (SEM) and Fourier‐transform infrared spectroscopy (FT‐IR). The chromatographic performance of the column was evaluated by hydrophilic interaction chromatography (HILIC). Amino acids were used as test solutes. The running buffer conditions for the enantioseparation were found to be 85% acetonitrile (ACN):10%MeOH: 5% H₂O at 0.1% v/v trifluoro acetic acid (TFA) (flow rate: 800 nL/min). The enantioseparation provided high theoretical plate numbers up to 26 000 platesm^?1. A good retention capacity within satisfactory retention times was also achieved. Real sample applicability of this column to the separation of amino acid enantiomers in fruit juice sample was demonstrated.     

Bioorganic Research of Galactites tomentosa Moench. Honey Extracts: Enantiomeric Purity of Chiral Marker 3‐Phenyllactic Acid

Thistle (Galactites tomentosa Moench.) honey organic extracts were obtained by headspace solid‐phase microextraction (HS‐SPME) and ultrasonic solvent extraction (USE) and analyzed by gas chromatography (GC‐FID and GC‐MS) for the first time. Most abundant headspace compounds were terpenes, particularly linalool derivatives (hotrienol was predominant with a range of 38.6–57.5%). 3‐Phenyllactic acid dominated in the solvent extracts (77.4–86.4%) followed by minor percentages of other shikimate pathway derivatives. After determination of an adequate enantioseparation protocol on Chirallica PST‐4 column, the honey solvent extracts were analyzed by high‐performance liquid chromatography (HPLC). The chiral analysis revealed high enantiomeric excess (>95%) of (–)‐3‐phenyllactic acid in all samples. Therefore, previous findings of chemical markers of thistle honey were extended, providing new potential for advanced chemical fingerprinting (optical pure chemical marker). Chirality 26:405–410, 2014. © 2014 Wiley Periodicals, Inc.     

Fast chiral separation of drugs using columns packed with sub‐2 μm particles and ultra‐high pressure

The use of columns packed with sub‐2 μm particles in liquid chromatography with very high pressure conditions (known as UHPLC) was investigated for the fast enantioseparation of drugs. Two different procedures were evaluated and compared using amphetamine derivatives and β‐blockers as model compounds. In one case, cyclodextrins (CD) were directly added to the mobile phase and chiral separations were carried out in less than 5 min. However, this strategy suffered from several drawbacks linked to column lifetime and low chromatographic efficiencies. In the other case, the analysis of enantiomers was carried out after a derivatization procedure using two different reagents, 2,3,4‐tri‐O‐acetyl‐α‐D ‐arabinopyranosyl isothiocyanate (AITC) and N‐α‐(2,4‐dinitro‐5‐fluorophenyl)‐L ‐alaninamide (Marfey's reagent). Separation of several amphetamine derivatives contained within the same sample was achieved in 2–5 min with high efficiency and selectivity. The proposed approach was also successfully applied to the enantiomeric purity determination of (+)‐(S)‐amphetamine and (+)‐(S)‐methamphetamine. Similar results were obtained with β‐blockers, and the separation of 10 enantiomers was carried out in less than 3 min, whereas the individual separation of several β‐blocker enantiomers was performed in 1 min or less. Chirality, 2010. © 2009 Wiley‐Liss, Inc.