Separation and determination of coumarins from Cacalia tangutica by capillary zone electrophoresis

Capillary zone electrophoresis (CZE), using a 20 mmol/L borate buffer at pH 10.5, was developed for the identification and determination of three coumarins--7-hydroxy-coumarin (HC), 7-hydroxy-8-methoxy-coumarin (HMC) and 7-O-beta-D-glucosyl-coumarin (GC)--in the extracts of the flower of Cacalia tangutica. Regression equations revealed linear relationships (correlation coefficient 0.9986-0.9990) between the corrected peak area (the ratio of peak area to migration time) of each constituent and its concentration. The relative standard deviations (RSD) of the migration time and peak area were 1.45-1.52 and 2.60-3.84% (intra-day), and 1.75-2.22 and 2.90-4.04% (inter-day), respectively. The recoveries of three constituents ranged between 94.5 and 105.6%. The effects of pH value, buffer concentration and applied voltage on the migration behavior of HC, HMC and GC were investigated. The contents of the three active constituents in the flower of Cacalia tangutica were successfully determined within 6 min under the optimum conditions chosen. Moreover, the dissociation constants for three coumarins were also determined by CE.     

Simultaneous determination of ofloxacin and ornidazole in pharmaceutical preparations by capillary zone electrophoresis

A simple, rapid and validated capillary electrophoretic method has been developed for the separation and determination of ofloxacin and ornidazole in pharmaceutical formulations with detection at 230 nm. Optimal conditions for the quantitative separations were investigated. Analysis times shorter than 4 min were obtained using a background electrolyte solution consisting of 25 mmol/L phosphoric acid adjusted with 1 m Tris buffer to pH 8.5, with hydrodynamic injection of 5 s and 20 kV separation voltage. The validation criteria for accuracy, precision, linearity and limits of detection and quantitation were examined and discussed. An excellent linearity was obtained in concentration range 25–250 µg/mL. The detection limits for ofloxacin and ornidazole were 1.03 ± 0.11 and 1.80 ± 0.06 µg/mL, respectively. The proposed method has been applied for the analysis of ofloxacin and ornidazole both individually and in a combined dosage tablet formulation. The proposed validated method showed recoveries between 96.16 and 105.23% of the nominal contents. Copyright © 2009 John Wiley & Sons, Ltd.     

毛细管区带电泳法同时分离测定香兰素和邻位香兰素异构体

建立了同时测定香兰素和其异构体邻位香兰素的毛细管区带电泳法(CZE)。考察了缓冲溶液的种类、浓度和pH以及分离电压等因素对分离结果的影响。在缓冲溶液为50 mmol/L硼砂-150 mmol/L磷酸氢二钠(pH 7.5)、分离电压15 kV的优化条件下,6 min内即可实现分离。香兰素和邻位香兰素在10～240 mg/L范围内线性关系良好,相关系数分别为0.9999和0.9997;方法的检出限均为1.0 mg/L (信噪比为3);样品的加标回收率为99.4%～101.2%,相对标准偏差为0.19%～0.73%。该方法操作简单、快速,已应用于实际样品的分析,并获得了令人满意的结果。     

Simultaneous determination of sulfamethoxazole and trimethoprim in human plasma by capillary zone electrophoresis

A capillary electrophoretic method for the simultaneous determination of sulfamethoxazole and trimethoprim in plasma was developed. Sulfamethoxazole and trimethoprim extracted from human plasma with ethyl acetate were analyzed at 20 kV and 25 degrees C using 15 mm phosphate buffer (pH 6.2) as the electrolyte. The detection was by UV at 220 nm. The run time was 8.0 min and the limit of quantification was 10.00 microg/mL for sulfamethoxazole and 2.00 microg/mL for trimethoprim. The recovery was >99% for both compounds. This method enabled the detection of sulfamethoxazole and trimethoprim in plasma of patients after oral ingestion of their combined formulation. The present simple and rapid method is applicable to drug monitoring in immunocompromised patients who are taking the combined formulation of these compounds for the treatment or prophylaxis of Pneumocystis carinii pneumonia.     

乙醛酸和草酸的毛细管区带电泳分析

建立了同时测定乙醛酸和草酸的毛细管区带电泳法。考察了缓冲溶液的种类、浓度和pH以及分离电压等因素对分离结果的影响。在缓冲溶液为20 mmol/L硼砂-5.5 mmol/L邻苯二甲酸氢钾(pH 9.0)、分离电压20 kV、检测波长212 nm的优化条件下,11 min内即可实现对目标物的分离。乙醛酸和草酸分别在0.8～20 g/L和1.2～20 g/L范围内线性关系良好,相关系数分别为0.9993和0.9975;方法的检出限分别为0.2和0.4 g/L(信噪比为3);样品的加标回收率为98.3%～102.5%,相对标准偏差为0.35%～0.61%。该方法操作简便、快速、成本低廉,已应用于实际样品的分析,并获得了令人满意的结果。     

Identification and determination of ecdysone and phenylpropanoid glucoside and flavonoids in Lamium maculatum by capillary zone electrophoresis

The simultaneous determination of 20-hydroxy ecdysone (1), 3,7-dimethoxy-quercetin (2), acteoside (3) and rutin (4) in the mixture of leaf and stem, and the flower of Lamium maculatum has been investigated by capillary zone electrophoresis for the first time. With an electrolyte containing 30 mmol/L borate, at pH 9.47 and 20 kV applied voltage, the four active compounds were completely separated within 5 min with satisfactory results. The effects of concentration of borate and electrolyte pH on electrophoretic behavior and separation were studied. Regression equations revealed linear relationships (correlation coefficients 0.9998-0.9999) between the peak area of each analyte and the concentration. The levels of analytes in the different parts of Lamium maculatum were easily determined with recoveries ranging from 98.3 to 105.0%.     

Analytical potential of enzyme-coated capillary reactors in capillary zone electrophoresis

Enzymes immobilized on the inner surface of an electrophoretic capillary were used to increase sensitivity and resolution in capillary zone electrophoresis (CZE). Sensitivity is enhanced by inserting a piece of capillary containing the immobilized enzyme into the main capillary, located before the detector, in order to transform the analyte into a product with a higher absorptivity. This approach was used to determine ethanol. In order to improve resolution, capillary pieces containing immobilized enzymes were inserted at various strategic positions along the electrophoretic capillary. On reaching the enzyme, the analyte was converted into a product with a high electrophoretic mobility, the migration time for which was a function of the position of the enzyme reactor. This approach was applied to the separation and determination of acetaldehyde and pyruvate. Finally, the proposed method was validated with the determination of ethanol, acetaldehyde, and pyruvate in beer and wine samples.     

Sub-femtomole determination of DABSYL-amino acids with capillary zone electrophoresis separation and laser-induced thermo-optical absorbance detection

Fifteen amino acids are determined as the DABSYL (4-4-dimethylaminoazobenzene-4'-sulfonyl chloride) derivative with capillary zone electrophoresis separation and low-power laser-induced thermo-optical detection. Separation efficiencies are on the order of 200 000 theoretical plates and the detection limit, 3 s, is 200 attomole of glycine injected onto the column. At the detection limit, 0.7 attomole of glycine is present within the 40 picoliter detection volume.     

Identification and determination of aesculin and aesculetin in ash barks by capillary zone electrophoresis

Summary A capillary zone electrophoresis method for identification and determination of aesculin and aesculetin has been established using borate-phosphate buffer containing 30% ethanol with on-column UV detection. A detailed investigation of the influence of changes in borate concentration, pH, applied voltage, temperature and organic modifier was then carried out. For both aesculin and aesculetin, a linear plot of migration time (MT) against borate concentration was obtained, and ln[measured peak area (MA)] and lnMT both gave linear plots against ln(applied voltage) with correlation coefficient r>0.999, which also resulted in a linear correlation between MA and MT (r≥0.9998) under varied voltage. Ethanol as organic modifier to the background electrolytes helped in separating aesculin and aesculetin from other components in ash barks. The reproducibility with relative standard deviation in MT and in normalized peak area(NA) and linearity based on NA against concentration were evaluated. Finally, the method was successfully applied to monitor the quality of different ash barks and to compare the effect of sample preparation on content of bioactive components in ash bark. Results indicate that CZE promises to be applicable to quality control of traditional Chinese medicines containing aesculin and aesculetin.     

毛细管区带电泳-间接紫外法快速测定食品中的甜蜜素

建立了毛细管区带电泳-间接紫外法快速测定食品中甜蜜素的新方法。液体样品用超纯水稀释后直接进样;固体样品经粉碎或剪碎后用超纯水超声提取后离心,上清液直接进样或用水稀释后进样。以未涂敷石英毛细管（80 cm×75 μm,有效长度：70 cm）为分离柱,以2 mmol/L苯甲酸钠+10 mmol/L碳酸钠+0.5 mmol/L十六烷基三甲基溴化铵为分离缓冲液;于200 nm波长处检测。检出限为8.9 mg/kg （S/N=3）,定量限为26.7 mg/kg （S/N=9）。低、中、高添加水平的加标回收率分别为93.4%、100.3%及101.9%,相应的RSD分别为6.7%、2.0%及2.2%（n=5）。日内及日间精密度分别为2.6%和4.5%。整个分析过程无需有机溶剂。在能力验证样品的分析结果与国家标准方法的结果相吻合的基础上,分析了7件食品样品,获满意结果。     

Optimization of capillary zone electrophoresis parameters for selenium speciation

The behaviour of four biologically relevant selenium compounds (Se(VI), Se(IV), selenomethionine and selenocystine) in capillary zone electrophoresis (CZE) was investigated. Parameters which affect the separation, detection and sample introduction were investigated to improve the sensitivity of the analysis. Short-term repeatability was evaluated and detection limits were found to be in the g·l^–1 range.     

Analysis of roller pen inks by capillary zone electrophoresis

The analysis of roller pen inks has become more and more important in fraudulent document examination because of the extensive use of roller pens in financial documents. Capillary electrophoresis with powerful resolution was applied for the analysis of roller pen inks. The experiment focused on the optimization of the separation of the extract from commercially available roller pen entries. A better separation electropherogram was obtained when a 20 mM borate buffer at pH 8.5 and a fused silica capillary with an inner diameter of 100 μm with a total length of 47 (40 cm to the detector window) were used. Five inks from roller pens of different manufacturers and countries were analyzed, and their electropherograms showed that most patterns are distinctly different from each other. Capillary with inner diameter of 100 μm increased the intensity of determination; therefore, color dyes were identified in the visible range and were able to provide more information for comparing types of roller pen inks.     

Pre-equilibrium capillary zone electrophoresis or frontal analysis: advantages of plateau peak conditions in affinity capillary electrophoresis

The feasibility of using the affinity CE methodologies pre-equilibrium CZE and CE frontal analysis was tested on interaction systems exhibiting rapid on-and-off kinetics. Experimentally, the methodologies differ only with respect to the volume of sample introduced into the capillary. Pre-equilibrium CZE has been considered amendable to interactions with slow on-and-off kinetics only; however, it has recently been applied in studies of interactions with fast on-and-off kinetics. The effect of varying the sample volume introduced hydrodynamically into the capillary on the apparent degree of complexation was studied. For two different binding systems, the fraction of free analyte was found to be overestimated using pre-equilibrium CZE as compared to volumes providing plateau peak conditions as used with frontal analysis. Results indicate that frontal analysis conditions lead to more robust binding assays and thus more reliable data. The validity of data obtained by pre-equilibrium CZE may be low, thus the use of an experimental setup providing plateau peaks is highly recommended. It is suggested that the effect of altering the sample volume on the degree of binding should be investigated as part of method development and validation.     

Determination of chlorite in drinking water by on-line coupling of capillary isotachophoresis and capillary zone electrophoresis

An isotachophoresis (ITP)–capillary zone electrophoresis (CZE) combination was used for the determination of chlorite in drinking waters. No sample preparation is needed and no interfering by other anions in tap water was observed. The reached limits of detection with conductivity detector were 0.012–0.017 mg l⁻¹. By four-fold sample loading with a 30 μl valve, 0.005 mg l⁻¹ of chlorite was determined with R.S.D.=3.3%. The concentrations of 0.05 and 0.20 mg l⁻¹ were measured with R.S.D. of 2.2 and 2.7%, respectively. The recoveries of chlorite from drinking water were 96–106% in the range of 0.02–0.20 mg l⁻¹. The R.S.D. values of migration times (inter-day) were up to 1.3%. The time for analysis is about 15 min.     

Simultaneous determination of atenolol,chlorthalidone and amiloride in pharmaceutical preparations by capillary zone electrophoresis with ultraviolet detection

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.     

Determination of chelating agents and metal chelates by capillary zone electrophoresis

Aminopolycarboxylic acids such as diethylenetriaminepentaacetic acid (DTPA) are commonly used as chelating agents in many pulp and paper industries, particularly as scavengers of metal ions which catalyze the decomposition of hydrogen peroxide used as a bleaching agent. Concern for the effect of waste DTPA in the aquatic environment has led to a need for the development of methods to determine its levels in waste water. This paper describes the determination of free DTPA and several metal-DTPA complexes in water and waste water by capillary zone electrophoresis. The optimization of separation conditions included the selection of an appropriate carrier electrolyte composition (pH, organic solvents, ion-pairing reagents) and the systematic investigations of selective complexation of free DTPA as well as metal exchange reactions for metal-DTPA complexes in order to achieve selective and sensitive direct UV detection. The determination of DTPA in waste water from a paper mill was possible in the low ppm range.     

Separation and determination of magnolol and honokiol inMagnolia officinalis bark by capillary zone electrophoresis

The effects of pH on separation parameters such as migration mobility, resolution, sensitivity, column efficiency and peak shape were emphatically studied. Better separation of magnolol and honokiol using capillary zone electrophoresis was achieved by optimizing pH in the range 5.0–11.7. The influences of applied voltage and temperature were also investigated. We adopted a better sample extraction procedure by which higher contents of honokiol and magnolol with sample compositions unchanged were obtained. The analysis was performed with direct UV detection using a 10 mM borate-10 mM phosphate buffer at pH of 11.6. The method was successfully applied to the simultaneous determination of magnolol and honokiol inMagnolia officinalis bark within 9 min.     

高效毛细管区带电泳法快速测定尿液中的肌酐

建立了一种快速测定尿中肌酐浓度的高效毛细管电泳方法。利用非涂层石英毛细管(64.5 cm×50μm i.d),以pH 2.5,0.1 mmol/L H3PO4作为电泳缓冲液,检测波长191 nm,用0.05 Pa压力进样4 s,在电压16 kV快速分离尿液中的肌酐,采用外标法定量。肌酐的迁移时间约为5.5 min,肌酐浓度在34.5~8840μmol/L范围内呈良好的线性(r2=0.999)。平均日内精密度为2.5%,日间精密度为3.0%。回收率94.1%~99.0%。与全自动生化分析仪碱性苦味酸速率法相比有良好的相关性(r=0.990,n=56)。高效毛细管电泳法测定尿肌酐可应用于临床样品的检测。     

毛细管区带电泳法拆分匹伐他汀钙对映体

建立了匹伐他汀钙对映体的毛细管区带电泳(CZE)拆分方法。分别考察了电泳电压,缓冲溶液种类、浓度及pH值,环糊精种类及浓度,添加剂种类及浓度等参数对实验结果的影响,从而确定了匹伐他汀钙对映体的最佳拆分条件: 电泳电压为18 kV;运行缓冲溶液为80 mmol/L的Tris-HCl缓冲体系,pH值为3.20,其中含有50 mmol/L HP-β-CD(羟丙基-β-环糊精)和5 mmol/L SDS(十二烷基磺酸钠);采用重力进样,进样高度17 cm,进样时间为2 s。在优化的实验条件下,匹伐他汀钙对映体得到了较好的分离,分离度可达2.17。实验结果表明该方法可用于匹伐他汀钙对映体的分离,具有快速、便捷、准确性好等优点。     

A quick method for the simultaneous determination of ascorbic acid and sorbic acid in fruit juices by capillary zone electrophoresis

A method of quickly determining ascorbic acid and sorbic acid by capillary zone electrophoresis with ultraviolet detection was developed. The choice of background electrolyte, wavelength, injection time and applied voltage were discussed. Ascorbic acid and sorbic acid were well separated in 80 mmol L⁻¹ boric acid-5 mmol L⁻¹borax (pH = 8.0) in 5 min at the detecting wavelength of 270 nm. Under the optimum condition, the method has linear ranges of 2.54-352.00 mg L⁻¹ for ascorbic acid and 1.08-336.39 mg L⁻¹ for sorbic acid with the detection limit of 1.70 mg L⁻¹ for ascorbic acid and 0.54 mg L⁻¹ for sorbic acid, respectively. Other organic acids in fruit juices have no effect on the detection. This method is very feasible and simple and can be used to detect ascorbic acid and sorbic acid in fruit juices.