Determination of chelating agents in Hanford tank waste simulant by capillary zone electrophoresis

A capillary electrophoretic method has been developed which achieves rapid quantitative separation and determination of ethylenediaminetetraacetic acid, N-(2-hydroxyethyl)ethylenediaminetriacetic acid, diethylenetriaminepentaacetic acid, ethylenediaminediacetic acid, and nitrilotriacetic acid in Hanford tank waste simulant (TWS). Direct UV detection of Cu²⁺/chelator complexes is used to achieve enhanced sensitivity. The qualitative and quantitative reliability of the method and the quality of separations, as given by efficiency and resolution, is presented. In addition, the limits of detection and linearity of detector response with concentration are given for each chelator. The selection of Cu as the UV-absorbing species over other transition metals present in the waste is discussed.     

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。     

Determination of free fatty acids by capillary zone electrophoresis

Capillary zone electrophoresis was investigated for the separation of free fatty acids as an alternative to well established techniques such as GC or HPLC. The analysis was performed with indirect UV detection in a counterelectroosmotic flow mode using a diethylbarbiturate carrier electrolyte at a pH between 10 and 11 in a mixed aqueous-organic solvent. Separation of saturated and unsaturated fatty acids could be achieved after bromination of the double bonds. Problems with wall adsorption of fatty acids could be overcome by increasing the temperature and using a high concentration of a zwitterionic reagent to inactivate the silica surface. Increased sensitivity could be achieved after preconcentration on alumina. The method was applied to the determination of free fatty acids in dairy products. The advantages compared to traditional methods include short analysis times and simple preparation steps.Dedicated to Univ. Prof. Dr. Karl Winsauer on the occasion of his 70th birthday     

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.     

毛细管区带电泳法测定粉针剂中头孢拉定的含量

用毛细管区带电泳法测定头孢拉定的含量 ,未涂层毛细管柱 (75 μm×48.5cm ,有效长度 40cm) ,电压 2 8kV ,检测波长 2 3 0nm ,温度 2 0℃ ,进样 5×1 0 3Pa× 3s。运行缓冲液为 2 5mmol/L硼砂缓冲液。方法的线性范围 3 1 .2 2μg/mL～ 749.2 8μg/mL ,检测限为 1 .1 7μg/mL。     

毛细管区带电泳法同时测定饮料中16种食品添加剂

建立了毛细管区带电泳法测定饮料中酸性红92、专利蓝V、荧光素二钠、酸性红1、靛蓝胭脂红、亮黑、丽春红6R、日落黄、苋菜红、柠檬黄等10种人工合成色素和苯甲酸、山梨酸、对羟基苯甲酸甲酯、对羟基苯甲酸乙酯、对羟基苯甲酸丙酯、对羟基苯甲酸丁酯等6种防腐剂的分析方法。考察了缓冲溶液种类、浓度、pH值及运行电压、温度等对分离的影响,确定最佳电泳条件为: 未涂层弹性石英毛细管柱(46 cm×50 μm),缓冲溶液为70 mmol/L硼酸(pH=9.5)(含体积分数为4%的乙腈),检测波长220 nm,电泳电压30 kV,进样时间5 s,电泳温度25 ℃。该法用于测定市售饮料样品得到满意结果: 在1～250 mg/L范围内线性关系良好,相关系数不小于0.9938,回收率在95.8%与108.7%之间。该法简便、准确,能够满足食品添加剂的常规检测要求。     

Metal ion capillary zone electrophoresis with direct UV detection: Comparison of different migration modes for negatively charged chelates

Summary Several migration modes suitable for capillary zone electrophoretic (CZE) separation of metal ions in the form of 8-hydroxyquinoline-5-sulphonic acid complexes are described and compared. Superior analysis time, resolution, efficiency and detectability were achieved using reversed movement of anionic metal complexes (in the anode-to-cathode direction) under the action of the electroosmotic flow. This method allows the CZE analysis of multicomponent mixtures of transition metal ions as well as aluminium within about six minutes.     

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.     

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.     

毛细管区带电泳技术快速分离检测爆炸残留物中的无机离子

利用间接紫外毛细管区带电泳方法完成了对爆炸残留物中7种无机离子(K+,NH+4,NO-2,NO-3,SO2-4,ClO-3,ClO-4)的分离检测。阳离子测定采用的缓冲体系为10 mmol/L吡啶（pH 4.5）-3 mmol/L冠醚,K+和NH+4在2.6 min内达到基线分离,检出限分别为0.25 mg/L和0.10 mg/L(S/N=3)。阴离子测定采用的缓冲体系为40 mmol/L硼酸-1.8 mmol/L重铬酸钾-2 mmol/L硼酸钠（pH 8.6）,氢氧化四甲铵为电渗流改性剂,5种阴离子在4.6 min内达到基线分离,检出限为0.10～1.85 mg/L。该方法已成功地应用于实际爆炸物样品种类的判定分析,取得了很好的结果。     

The determination of chlorophenols in waste water by capillary zone electrophoresis with an organic modifier

Summary Acapillary zone electrophoretic method has been optimized to improve selectivity and resolution in the analysis of chlorophenols in waste water. Use of a buffer system containing organic solvent dramatically improved the separation of chlorophenols. It was shown that selectivity was strongly affected by electrolyte pH and the presence of organic modifiers. The results show that the determination of all seventeen chlorinated derivatives of phenol in water can be achieved by use of a single organic modifier. For example, with acetone as organic modifier all 17 chlorophenols could be separated and determined within 20 min. The standard deviation of migration times and peak areas of the chlorophenols were in the ranges 0.48–0.67% and 3.9–5.1% respectively. Detection linear ranges covered two orders of magnitude of concentration with correlation coefficients of 0.998–1.000, except for 4-chlorophenol. Quantitative aspects of capillary zone electrophoresis are also discussed. It was concluded that capillary zone electrophoresis is a potential method for determination of chlorophenol pollutants in waste water.     

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.     

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.     

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。     

毛细管区带电泳法分析不同来源血竭中龙血素A和龙血素B

在系统优化了电解质溶液的pH、组成、浓度及仪器条件的基础上,建立了一种测定不同来源血竭中龙血素A和龙血素B的毛细管区带电泳(CZE)方法。采用20 kV的分离电压,25 ℃的毛细管柱温,211 nm的检测波长以及5 s的压力(3447 Pa)进样时间,在20 mmol/L的Na2B4O7缓冲溶液(用NaOH调节pH到9.98,含有10%(v/v,下同)乙腈、5.0%乙二醇和1.0%正丁醇)中,龙血素A和龙血素B在15 min内得到了有效分离与检测。方法的线性范围对于龙血素A和龙血素B分别为1.0～100.0 mg/L和0.5～100.0 mg/L。将该方法用于天然血竭及人工诱导血竭中龙血素A和龙血素B的测定,相对标准偏差在0.6%～3.8%之间,加标回收率在95.1%～105.8%之间。方法具有简单、快速、重现性较好和准确度较高的优点,可以用于血竭样品中龙血素A和龙血素B的测定。     

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.     

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.     

Determination of phenolic acids by capillary zone electrophoresis and HPLC

Selected phenolic acids are determined by capillary zone electrophoresis and HPLC, each using UV detection. The optimised CZE background electrolyte contained 50 mM acetic acid, 95 mM 6-aminocaproic acid, 0.1% polyacrylamide, 1% polyvinylpyrrolidone, and 10% methanol. Twelve phenolic acids (gallic, p-hydroxybenzoic, 3,4-dihydroxybenzoic, vanillic, syringic, o-coumaric, p-coumaric, caffeic, sinapic, ferulic, salicylic and chlorogenic) were separated within 10 minutes. Chromatographic separation of these phenolic acids was carried out on an Eclipse XBD C8 column using a mobile phase gradient (acetonitrile / methanol / water / 0.1% phosphoric acid); all were separated within 25 minutes. Electrophoretic and chromatographic determinations of ferulic and chlorogenic acids were compared on barley, malt, and potato samples. The methods’ characteristics were: linearity (1–20 mg ml and 0.2–4 mg ml⁻¹), accuracy (recovery 94 ± 5% and 96 ± 4%), intra-assay repeatability (4.1% and 3.5%), and detection limit (0.2 and 0.02 mg ml⁻¹).      

毛细管区带电泳技术快速分离检测爆炸残留物中的无机离子

利用间接紫外毛细管区带电泳方法完成了对爆炸残留物中7种无机离子(K+,NH+4,NO-2,NO-3,SO2-4,ClO-3,ClO-4)的分离检测。阳离子测定采用的缓冲体系为10 mmol/L吡啶（pH 4.5）-3 mmol/L冠醚,K+和NH+4在2.6 min内达到基线分离,检出限分别为0.25 mg/L和0.10 mg/L(S/N=3)。阴离子测定采用的缓冲体系为40 mmol/L硼酸-1.8 mmol/L重铬酸钾-2 mmol/L硼酸钠（pH 8.6）,氢氧化四甲铵为电渗流改性剂,5种阴离子在4.6 min内达到基线分离,检出限为0.10～1.85 mg/L。该方法已成功地应用于实际爆炸物样品种类的判定分析,取得了很好的结果。