用高效液相色谱手性固定相法拆分芳香仲醇及芳香乙二 醇类手性化合物

在ChiralcelOD和ChiralcelOJ两支多糖类手性固定相上，以各种不同配比的正己烷-异丙醇为洗脱剂对38种带有不同取代基的芳香仲醇及芳香乙二醇类手性化合物的对映体进行拆分，考察了这些外消旋体在这两支手性柱上的色谱行为。结果表明，扬长避短一柱对这些化合物的拆分能力与化合物取代基的性质和位置有关，这些化合物与手性固定相之间的氢键作用和π-π作用是影响手性拆分的重要原因。拆分方法已应用于潜手性酮不对称还原产物的光学纯度的鉴定，并取得了很好的效果。     

HPLC法拆分粉唑醇对映体

HPLC法拆分粉唑醇对映体;粉唑醇;对映体;分离;手性固定相     

Chiral resolution of flurbiprofen and ketoprofen enantiomers by HPLC on a glycopeptide-type column chiral stationary phase

Vancomycin is an amphoteric, glycopeptide, macrocyclic antibiotic. When attached to 5 microspherical silica gel, vancomycin proved to be an effective chromatographic chiral stationary phase that could be used in the reversed-phase mode. In this study, a bonded vancomycin chiral stationary phase (Chirobiotic Vtrade mark) was investigated for the chiral liquid chromatography analysis of ketoprofen and flurbiprofen. The selectivity factor (alpha) and the chiral resolution factor (RS) of Chirobiotic Vtrade mark were evaluated first as a function of the buffer pH and molarity, and second as a function of organic modifier type and composition of the mobile phase. Four organic modifiers (tetrahydrofuran, 2-propanol, 1,4-dioxane and methanol) have been tested for their selectivity. Optimized conditions using 20% of tetrahydrofuran in ammonium nitrate (100 mM, pH 5) were selected for the enantioseparation of flurbiprofen and ketoprofen from their racemic forms. At pH 5, these acidic compounds are almost negatively charged, while the chiral selector possesses a positive charge allowing it to interact electrostatistically with the analytes. Using these chromatographic conditions, the column stability was excellent over several months of experiments.     

Enantiomeric resolution of underivatized small peptides by HPLC with a chiral crown ether stationary phase

Factors influencing the stereoisomeric resolution of underivatized dipeptides and a representative tripeptide on Crownpak (CR) columns have been investigated. The elution order and relative retention suggest that a combination of chiral, steric, and hydrophobic interactions effects the extent of chiral recognition and the retention achieved during separations. Some dipeptides whose amine terminus is located three atoms from the asymmetric center (such as dipeptides of D ,L -glycine) were resolved, but the elution order was the opposite of that expected for the type of Crownpak column used (CR(+)). Peptides containing hydrophobic substituents were strongly retained, but their retention times could be significantly reduced, and detectability improved, by use of gradient elution. Analysis of a commercial sample of D ,L -leucine-D ,L -alanine revealed the stereoisomers to be present in an unexpected quantitative ratio and demonstrated the utility of these separations for quality assurance and quantitative analyses.     

高效液相色谱法对外消旋药物的拆分

综述了近年来高效液相色谱法在药物对映体拆分与测定中的应用，介绍了许多有代表性的具有不同药理性能对映异构体药物，并指出出拆份的重要意义，共引用文献３２篇。     

Enantiomeric resolution of 2-arylpropionic acid nonsteroidal anti-inflammatory drugs by capillary electrophoresis: methods and applications

The 2-arylpropionic acids (2-APAs) are an important group of nonsteroidal anti-inflammatory drugs. These agents, the majority of which are available as racemates, exhibit stereoselectivity in both their action and disposition. Developments in stereoselective separation science methodology, mainly chromatographic, have facilitated an evaluation of the pharmacological properties of the individual enantiomers of these drugs and contributed to our understanding of both their mode(s) of action and disposition. While a number of electrophoretic techniques, including capillary electrophoresis, capillary electrochromatography and isotachophoresis, have been applied to the stereoselective resolution and stereospecific analysis of these agents using a variety of chiral selectors, e.g., cyclodextrins, oligosaccharides, macrocyclic antibiotics, and proteins, the number of published applications in pharmaceutical and biomedical analysis remains relatively limited. However, the utility of electrophoretic techniques for stereospecific analysis may be illustrated using the 2-APAs as typical examples of chiral acidic pharmaceuticals. Applications include: determination of enantiomeric composition following biosynthetic stereoselective hydrolysis; examination of both achiral and chiral impurity profiles in bulk drugs and formulated products; determination of enantiomeric impurities in both bulk drugs and formulated products; examination of configurational stability following stress testing of formulated products; determination of enantiomeric composition and metabolite profile in biological fluids following administration of the racemates and individual enantiomers. It may be anticipated that future exploitation of electrophoretic approaches to the stereospecific analysis of these agents will result in further contributions to our understanding of their stereoselective biological properties and therapeutic use.     

Enantiomeric resolution of bifonazole by supercritical fluid chromatography

The enantiomeric separation of bifonazole by supercritical fluid chromatography on Chiralpak AD has been studied. The effect of different modifiers (methanol, ethanol, 2-propanol, and acetonitrile) was examined. Enantioseparation was possible with all of them, but the best results were provided by the alcohol-type ones. The resolution was higher than 5 in all cases. The isoelution temperatures Tiso were calculated from the study of the temperature effect for the different organic modifiers. The value of Tiso was below the working temperature range on using methanol, but above it with ethanol or 2-propanol.     

Enantiomeric resolution of albuterol sulfate by preferential crystallization

Albuterol is a β₂-adrenoceptor agonist prescribed for the treatment of bronchial asthma; it exists as a racemate and its bronchodilator activity resides in the (R)-isomer or levalbuterol. The aim of this study was to determine a methodology that would separate the enantiomers of albuterol by preferential crystallization after a conglomerate is identified within its derivatives. We found that albuterol sulfate behaves as a conglomerate showing the characteristic α_x-value = 2 (mole fraction solubility ratio of racemate vs enantiomer), the V-shaped ternary phase diagram and the preferential crystallization by seeding with the pure enantiomer. On the basis of these characteristics, we separated the enantiomers by entrainment, and crystallizing out a saturated methanolic solution of albuterol sulfate at 15 °C.     

Enantioselective analysis of ibuprofen in human plasma by anionic cyclodextrin-modified electrokinetic chromatography

This paper reports the development of a rapid method for the enantioselective analysis of the nonsteroidal anti-inflammatory drug ibuprofen in human plasma by capillary electrophoresis employing the anionic cyclodextrin-modified electrokinetic chromatography mode. Sample cleanup was carried out by acidification with HCl followed by liquid-liquid extraction with hexane:isopropanol (99:1 v/v). The complete enantioselective analysis was performed within 10 min, using 100 mmol L(-1) phosphoric acid/triethanolamine buffer, pH 2.6, containing 2.0% w/v sulfated beta-cyclodextrin as chiral selector; fenoprofen, another nonsteroidal anti-inflammatory drug, was used as internal standard. The calibration curves were linear over the concentration range of 0.25-125.0 microg mL(-1) for each enantiomer of ibuprofen. The mean recoveries for ibuprofen enantiomers were up to 85%. The enantiomers studied could be quantified at three different concentrations (0.5, 5.0 and 50.0 microg mL(-1)) with a coefficient of variation and relative error not higher than 15%. The quantitation limit was 0.2 microg mL(-1) for (+)-(S)- and (-)-(R)-ibuprofen using 1 mL of human plasma. The plasma endogenous compounds and other drugs did not interfere with the present assay. The analysis of real plasma samples obtained from a healthy volunteer after administration of 600 mg of racemic ibuprofen showed a maximum plasma level of 29.6 and 39.9 microg mL(-1) of (-)-(R)- and (+)-(S)-ibuprofen, respectively, and the area under plasma concentration-time curve AUC(0-infinity) (+)-(S)/AUC(0-infinity) (-)-(R) ratio was 1.87.     

Selective quantification of ambroxol in human plasma by HPLC

The bronchosecretolytic drug ambroxol can be reliably quantified in human plasma by high performance liquid chromatography. Plasma is buffered alkaline, extracted with ether, and the organic solvent back-extracted with diluted acid. An automatically sampled aliquot is separated by reversed phase HPLC; the analyte is well separated from two metabolites that interfered strongly in earlier methods. UV detection at 230 nm enables a lower limit of quantitation of 5 ng/ml. Internal standardization with propranolol allows accurate and precise quantification. Evaluation of the optimized combination of mobile and stationary phase is described, and application of the method to experimental and clinical pharmacokinetic studies is illustrated.     

高效液相色谱法测定右旋雷贝拉唑钠的对映体纯度

采用高效液相色谱法测定右旋雷贝拉唑钠对映体的纯度。以α1-酸性糖蛋白键合硅胶为填充剂的CHIRALPAK-AGP手性柱为固定相,用乙腈-pH 6.0磷酸盐(1+9)混合溶液为流动相进行洗脱,用紫外检测器进行测定,检测波长为285nm。左旋雷贝拉唑钠的质量浓度在38.4~576μg·L-1范围内与其峰面积呈线性关系,检出限(3S/N)为0.2ng,测定下限(10S/N)为0.56ng。加标回收率在91.1%~102%之间,测定值的相对标准偏差在2.4%~4.3%之间。     

HPLC microdetermination of flurbiprofen enantiomers in plasma with a glycopeptide-type chiral stationary phase column

A rapid and stereospecific HPLC micromethod to quantify flurbiprofen enantiomers was developed. Both flurbiprofen enantiomers and indomethacin, used as internal standard, were extracted with methylene chloride from 100 microL of acidified plasma. The resolution of the R- and S-forms was performed on a bonded vancomycin chiral stationary phase (Chirobiotic V) with 20% of tetrahydrofuran in ammonium nitrate (100 mM, pH 5) as mobile phase. Calibration curves were linear in the range 0.5-10 microg/mL for both enantiomers. A good accuracy (< or = 5%) was obtained for all quality controls, with intra-day and inter-day variation coefficients equal or less than 7.7%. Recovery of both enantiomers was found in the range 77.4-86.3%. The lower limit of quantitation was 0.25 microg/mL for both enantiomers, without interference of endogenous components. This validated micromethod has been successfully applied for quantifying R- flurbiprofen and S- flurbiprofen in rat plasma.     

Enantiomeric resolution of bupivacaine by high-performance liquid chromatography and chiroptical detection

This work reports a new analytical procedure for the separation and determination of the enantiomers of bupivacaine and the determination of the enantiomeric purity. The isomers were separated using a Chirex 3020 (250 mm x 4.6 mm) with a mobile phase of n-hexane:dichloroethane:ethanol (82:9:9, v/v/v) at a flow-rate of 1 ml min(-1) and UV, polarimetric and circular dichroism (CD) detection. Obtained retention times were 5.93 and 7.53 min (R and S) with a resolution of Rs=2.36. Precisions (RSD) were 1.83 and 2.02% (CD detection) and 3.07 and 1.26% (UV detection) for R- and S-enantiomers, respectively (at 10 microg level). Detection limits were 0.5 and 0.5 microg (R and S) with CD detection, and 0.9 and 0.3 microg with UV detection. Polarimetric detection was inadequate to perform a quantitative method at similar concentration ranges as UV and CD because of poor sensitivity. A procedure for determination of enantiomeric purity using a conventional chromatographic column (RP18, Luna) coupled to a CD detector and anisotropy factor (CD/UV) as analytical signal was also developed. Obtained results show that RSDs of 6.7-1.6% were obtained in the range of 0-100% enantiomeric purity.     

Drug screening in human plasma by cloud-point extraction and HPLC

Cloud-point extraction (CPE) with RP-HPLC/DAD detection was used to develop a screen for six model basic drugs (paracetamol, promazine, amitriptyline, nortriptyline, clomipramine and chlorpromazine) in human plasma. These drugs’ varied hydrophobicities entail different affinities for the micelle-rich phase and CPE extraction efficiencies. Extraction recovery (except paracetamol) was above 80% and reproducibility (RSD%) ranged from 2.88 to 10.26 intraday and from 3.12 to 12.33 interday. The limits of detection were: 0.125 μg mL^?1 (promazine and chlorpromazine), 0.25 μg mL^?1 (amitriptyline and nortriptyline) and 0.5 μg mL^?1 (paracetamol and clomipramine). The method was linear over the ranges: 0.125–1.0 μg mL^?1 (promazine and chlorpromazine), 0.25–1.0 μg mL^?1 (amitriptyline and nortriptyline), 0.5–1.0 μg mL^?1 (clomipramine) and 0.5–10 μg mL^?1 (paracetamol). The procedure is a good alternative to the SPE or LLE sample preparation usually used.