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201.
Nine different chiral columns based on covalently immobilized or coated tris(3,5‐dimethylphenylcarbamate) cellulose and amylose have been explored. We evaluated their respective enantioselective potential including the enantioseparation and qualitative characteristics of peaks. The generic screening conditions were using gradient elution from 5 to 40% organic modifier/CO2 during 3 min with about 40 enantiomer pairs. Primary screening was carried out using ten different mobile phases varying in type of additives while using one representative amylose‐ and one cellulose‐based column. The complete evaluation of all nine columns was then carried out using three best performing organic modifiers: (1) methanol + 0.1% trifluoroacetic acid + 0.1% diethylamine, (2) isopropanol + 0.1% trifluoroacetic acid + 0.1% diethylamine, and (3) methanol + 0.1% ammonium hydroxide. Equivalency of different columns with the same chiral selector was not confirmed. Columns with the same stationary phase but different supports or manufacturing methods displayed differences in enantioselectivity and general performance. The similarity corresponded to 62 and 63% for the three cellulose‐coated columns taking CEL1 as the reference. The similarity was 67% for the pair of amylose‐based coated columns. For immobilized columns, the similarity was 69 and 59% for celluloses and amyloses pairs, respectively. The best performing column based on success rate of enantioseparation was Chiralcel OD‐3 when using methanol + 0.1% trifluoroacetic acid and 0.1% diethylamine combined additive. 相似文献
202.
《Biomedical chromatography : BMC》2017,31(8)
Tetrahydro‐α ‐(1‐methylethyl)‐2‐oxo‐1(2H)‐pyrimidineacetic acid (TPA) is a critical intermediate in the synthesis of HIV protease inhibitors. A simple and efficient method for the separation and determination of TPA enantiomers was developed. The TPA was separated into its enantiomers with an enantiomeric purity of 99% using an HPLC system equipped with a Chiralpak OD‐H column. Semi‐preparative HPLC enantioseparations were carried out for further enrichment of the enantiomers. The validity of this method was evaluated on the basis of its precision, accuracy, linearity and recovery. The method was observed to be suitable for the rapid separation and semi‐preparation of TPA isomers. The separated enantiomers were identified by optical rotation and high‐resolution electrospray ionization mass spectrometry. Furthermore, the stereochemical structures of the TPA enantiomers were definitively confirmed using a combination of experimental and calculated electronic circular dichroism spectra. The toxicity of the separated pure enantiomers against Oryzias melastigma was evaluated using the median lethal concentration (LC50) values. The results indicated that (S )‐(−)‐TPA is ~2.5 times more toxic than its enantiomorphism. 相似文献
203.
《Journal of separation science》2017,40(23):4645-4652
Nornicotine, an alkaloid constituent of tobacco, is a precursor to the carcinogen N‐nitrosonornicotine that is produced during the curing and processing of tobacco. Accumulating evidence reveals that nornicotine enantiomers have different neurochemical and behavioral effects. In the present study, an accurate and rapid method was developed for the enantioseparation of (R )‐(+)‐nornicotine and (S )‐(−)‐nornicotine enantiomers in tobacco by ultra‐performance convergence chromatography with tandem mass spectrometry. Chromatographic conditions were investigated to achieve the optimal resolution of two enantiomers. Results indicated that (R )‐(+)‐nornicotine and (S )‐(−)‐nornicotine could be separated within 5 min when ammonium hydroxide was added into the cosolvent, and the best resolution (R s = 4.76) was achieved on a immobilized cellulose tris‐(3,5‐dichlorophenylcarbamate) chiral stationary phase. The proposed method was validated and was finally applied to analyze the compositions of (R )‐(+)‐nornicotine and (S )‐(−)‐nornicotine in three typical types of tobaccos (flue‐cured, burley, and oriental). It was found that, enantiomer fraction of nornicotine (the proportion of (S )‐(−)‐nornicotine in the nornicotine pool) in burley tobacco samples was relatively high and constant compared with flue‐cured and oriental tobaccos. The effective and rapid enantioseparation of nornicotine may help the understanding of alkaloid metabolites in different tobacco varieties and may also benefit pharmacological studies of alkaloid enantiomers. 相似文献
204.
1,3-氧氮杂环戊烷类化合物在Chiralcel OD上的对映异构体拆分 总被引:1,自引:0,他引:1
2位取代的5-氯甲基-1,3-氧氮杂环戊烷衍生物具有两个手性中心,有多种生理和生物活性.利用Chiralcel OD手性柱,首次对通过非手性选择性合成的2,3-二苯基-5-氯甲基-1,3-氧氮杂环戊烷和2-(4′-硝基苯)-3-苯基-5-氯甲基-1,3-氧氮杂环戊烷进行手性拆分研究.考察了流动相中极性添加剂以及柱温对拆分的影响.初步探讨了其手性识别的作用机理.发现在正相体系下溶质的4个对映异构体都获得了很好的拆分. 相似文献
205.
采用高效液相色谱法在装有大环糖肽抗生素键合相的手性柱上拆分了7种氨基带有芴甲氧羰基(fluorenylmethoxycarbonyl,Fmoc)保护的氨基酸对映体。比较了Fmoc-缬氨酸和相应的不带保护基的缬氨酸对映体在不同流动相体系中的色谱保留行为;考察了甲醇-醋酸-三乙胺流动相体系中醋酸和三乙胺的浓度以及它们二者的浓度之比对N-Fmoc氨基酸对映体拆分效果的影响。实验结果表明分离温度及流动相流速的变化也会对分离结果产生影响。该法简便快速,已成功地用于这类氨基酸的光学纯度测定。 相似文献
206.
Green high‐performance liquid chromatography enantioseparation of lansoprazole using a cellulose‐based chiral stationary phase under ethanol/water mode 下载免费PDF全文
Rosella Ferretti Leo Zanitti Adriano Casulli Roberto Cirilli 《Journal of separation science》2016,39(8):1418-1424
A simple and environmentally friendly reversed‐phase high‐performance liquid chromatography method for the separation of the enantiomers of lansoprazole has been developed. The chromatographic resolution was carried out on the cellulose‐based Chiralpak IC‐3 chiral stationary phase using a green and low‐toxicity ethanol‐aqueous mode. The effects of water content in the mobile phase and column temperature on the retention of the enantiomers of lansoprazole and its chiral and achiral related substances have been carefully investigated. A mixed‐mode hydrophilic interaction liquid chromatography and reversed‐phase retention mechanism operating on the IC‐3 chiral stationary phase allowed us to achieve simultaneous enantioselective and chemoselective separations in water‐rich conditions. The enantiomers of lansoprazole were baseline resolved with a mobile phase consisting of ethanol/water 50:50 without any interference coming from chiral and achiral impurities within 10 min. 相似文献
207.
208.
M. Şerif Cansever Nevin Öztekin Ertuğrul Kıykım Tanyel Zübarioğlu Ayşe Çiğdem Aktuğlu Zeybek 《Journal of separation science》2023,46(16):2300145
2-hydroxyglutaric aciduria is an inherited neurometabolic disorder with two major types: D-2-hydroxyglutaric aciduria and L-2-hydroxyglutaric aciduria. An easy and fast capillary electrophoresis system combined with a capacitively coupled contactless conductivity detection method was developed for the enantioseparation and determination of D- and L-2-hydroxyglutaric acid in urine. D- and L-2-hydroxyglutaric acids were separated using vancomycin as the chiral selector. The optimal separation conditions for enantiomers were achieved by the use of a buffer containing 50 mM 4-(N-morpholino) butane sulfonic acid solution (pH 6.5), an electroosmotic flow modifier (0.001% [w/v] polybrene), and 30 mM vancomycin as chiral selector. The analysis time was 6 min under optimal conditions. The optimized and validated method was successfully implemented for quantifying D- and L-2-hydroxyglutaric aciduria in patients’ urine, without any pretreatment step. The linearity of the method was determined to be in the range of 2–100 mg/L for D- and L-2-hydroxyglutaric acid in urine. The precision (relative standard deviation%) was obtained at about 7%. For D- and L-2-hydroxyglutaric acids, the limits of detection were 0.567 and 0.497 mg/L, respectively. 相似文献
209.
Ruike Song Yanxia Li Yiting Chen Zhenli Qiu Lu Huang 《Journal of separation science》2023,46(8):2201039
A chiral covalent organic framework was synthesized, characterized, and incorporated into organic polymer monolithic capillary columns to provide chiral stationary phases for enantioseparations. The prepared monolithic capillary columns were characterized by scanning electron microscopy and elemental analysis. To obtain better enantioseparations, the columns’ preparation conditions, and enantioseparation conditions were optimized. Baseline resolutions of several chiral compounds were obtained with good reproducibility and stability. Furthermore, the mechanism of chiral recognition was investigated using molecular docking with AutoDock. Docking results showed that the enantioselectivity factor rather than resolution is correlated with the binding free energy difference between enantiomers with the chiral covalent organic framework. And abundant acetoxy and nitrile groups as well as benzene rings in the chiral covalent organic framework are responsible for the enantioseparation ability of the chiral monolithic capillary columns. 相似文献
210.
Cserháti T 《Biomedical chromatography : BMC》2008,22(6):563-571
The new achievements in the employment of native and derivatised cyclodextrins in various electrically driven chromatographic systems are compiled. Cyclodextrin-assisted separation techniques are concisely described and critically evaluated with special emphasis on the separation of enantiomer pairs. 相似文献