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991.
992.
A method based on cyclodextrin-mediated micellar electrokinetic chromatography (CD-MEKC) was developed and validated for quantification
of the minor, undesired enantiomer (distomer) in the drug candidate PHA-549184, an oxazolidinone that was under development
as an antibiotic. The low intrinsic solubility of the compound (0.24 mg mL−1), combined with the poor solution concentration sensitivity of capillary electrophoresis, required extensive method development
to enhance the solubility of PHA-549184 while minimally degrading electrophoretic performance. A number of approaches were
investigated, including inclusion of neutral and charged cyclodextrins in the background electrolyte (BGE) and addition of
both charged and neutral surfactants. The final BGE contains the nonionic surfactant Brij 35: pH 2.5, 18.8 mM lithium phosphate
buffer/5% highly sulfated-γ-CD/7.5 mM Brij 35. Quantitation is versus an external standard in the presence of an internal standard. The assay is selective
for the distomer and proved linear with a mean recovery of 104.0% over the range 0.25–2.0%. The LOD was 0.1, and the LOQ 0.2%,
both slightly higher than customary in chiral analysis, a consequence of an upper bound of 1.5 mg mL−1 placed on the sample concentration in order to maintain high efficiency for the system. Precision examined over the range
0.2–1.0% varied between 3.8% and 8.0%. No batch of drug substance registered above the detection limit for the distomer. 相似文献
993.
Rapid Preparation of Monolithic Columns for Capillary Electrochromatography Separation 总被引:1,自引:0,他引:1
Wen Jun GONG Yi Jun ZHANG Yu Ping ZHANG Seong Ho CHOI 《中国化学快报》2006,17(6):813-816
Sol-gel technology can provide a versatile approach to the synthesis of organic polymers and organic-inorganic hybrid materials applied in HPLC, micro-HPLC and capillary electrochromatography (CEC)1. It can take place under extraordinarily mild thermal co… 相似文献
994.
The differential version of the method of capillary rise has been used to measure the capillary constant and calculate the surface tension of methane-nitrogen solutions. Experiments have been conducted in the temperature range from 95 to 170 K at pressures up to 4 MPa. Experimental data on surface tension have been compared with the results of calculations by thermodynamic models. Equations are given which describe the dependence of the capillary constant of a solution on its temperature and composition. 相似文献
995.
During the last years (2000–2014), many publications concerning the forensic analysis of questioned documents have been published, and new techniques and methodologies are nowadays employed to overcome forensic caseworks. This article reviews a comprehensive collection of the works focused on this issue, including dating studies, the analysis of inks from pens and printers, the analysis of paper, the analysis of other samples related to questioned documents and studies on intersecting lines. These sections highlight the most relevant analytical studies by a wide range of analytical techniques. Separation and spectrometric techniques are critically discussed and compared, emphasizing the advantages and disadvantages of each one. Finally, concluding remarks on the research published are included. 相似文献
996.
《Biomedical chromatography : BMC》2017,31(9)
Capacitively coupled contactless conductivity detection (C4D) has appeared as a powerful technique for the detection of compounds lacking chromogenic or fluorogenic group. Since our last review (Biomedical Chromatography 2014; 28 : 1502–1506) several new capillary electrophoresis (CE)‐C4D methods have been reported. This review provides an update of the most recent utilization of CE‐C4D in the field of pharmaceutical, biomedical and food analysis covering the period from February 2014 to October 2016. The use of CE with C4D in the pharmaceutical field has been shown in many papers. Examples illustrate the applicability of CE‐C4D in the fields of pharmaceutical, biomedical and food analysis. Finally, general conclusions and perspectives are provided. 相似文献
997.
在同系物方法测定胶束迁移速度(l/tm c ) 的基础上提出了一种同时求算电渗流速率(l/t0) 的t0 和tm c 的新方法, 该法在选择同系物标记物较为适当时, 可以得到更为准确的结果。同时可以减少由t0 测定而带来的误差。 实验结果表明, 采用甲醇等标记物测定电渗流速率时, 由于其在胶束中的溶解使得实测结果较真值偏大,而由此计算得到的tm c 值偏低。t0 、tm c 皆与缓冲液的种类和浓度有关, 这可能是由于缓冲液组成的变化不仅使得离子强度改变, 也使柱管壁和胶束表面的ξ势发生变化所致。同系物标记物的选择对t0 、tmc 测定精度影响的讨论也为实际分析系统t0 、tmc 的测定和分析分离条件的优化选择提供了必要的理论依据。 相似文献
998.
《Journal of separation science》2017,40(8):1805-1814
Cefepime monitoring in deproteinized human serum and plasma by micellar electrokinetic capillary chromatography and liquid chromatography coupled to mass spectrometry in presence of other drugs is reported. For micellar electrokinetic capillary chromatography, sample preparation comprised dodecylsulfate protein precipitation at pH 4.5 using an increased buffer concentration compared to that of a previous assay and removal of hydrophobic compounds with dichloromethane. This provided robust conditions for cefepime analysis in the presence of sulfamethoxazole and thus enabled its determination in samples of patients that receive cotrimoxazole. The liquid chromatography assay is based upon use of a column with a pentafluorophenyl‐propyl modified and multiendcapped stationary phase and the coupling to electrospray ionization with a single quadrupole detector. The performances of both assays with multilevel internal calibration were assessed with calibration and control samples and both assays were determined to be robust. Cefepime levels monitored by micellar electrokinetic capillary chromatography in samples from patients that were treated with cefepime only and with cefepime and cotrimoxazole were found to compare well with those obtained by liquid chromatography coupled to mass spectrometry. Cefepime drug levels determined by micellar electrokinetic capillary chromatography could thereby be validated. 相似文献
999.
1000.
Khaldun M. Al Azzam Bahruddin Saad Hassan Y. Aboul‐Enein 《Biomedical chromatography : BMC》2010,24(9):977-981
Capillary zone electrophoresis methods for the simultaneous determination of the β‐blocker drugs, atenolol, chlorthalidone and amiloride, in pharmaceutical formulations have been developed. The influences of several factors (buffer pH, concentration, applied voltage, capillary temperature and injection time) were studied. Using phenobarbital as internal standard, the analytes were all separated in less than 4 min. The separation was carried out in normal polarity mode at 25°C, 25 kV and using hydrodynamic injection (10 s). The separation was effected in an uncoated fused‐silica capillary (75 μm i.d. × 52 cm) and a background electrolyte of 25 mm H3PO4 adjusted with 1 m NaOH solution (pH 9.0) and detection at 198 nm. The method was validated with respect to linearity, limit of detection and quantification, accuracy, precision and selectivity. Calibration curves were linear over the range 1–250 μg/mL for atenolol and chlorthalidone and from 2.5–250 μg/mL for amiloride. The relative standard deviations of intra‐ and inter‐day migration times and corrected peak areas were less than 6.0%. The method showed good precision and accuracy and was successfully applied to the simultaneous determination of atenolol, chlorthalidone and amiloride in various pharmaceutical tablets formulations. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献