Monitoring diclofenac sodium in single human erythrocytes introduced by electroporation using capillary zone electrophoresis with electrochemical detection.

A method for determination of the drug diclofenac sodium introduced into individual human erythrocytes by electroporation using capillary zone electrophoresis with electrochemical detection at a carbon fiber array microelectrode was developed. In this method, the whole cell was injected into the separation capillary by electromigration. Cell lysis was accomplished by injecting a plug of the separation buffer (1.25 x 10(-2) mol/L Na2B4O7-3.13 x 10(-3) mol/L NaOH). The optimum conditions of separation and detection were 20 kV for the separation voltage and 1.0 V for the detection potential. The concentration of diclofenac sodium in the single cells was quantified by a calibration curve. The mean concentration of diclofenac sodium introduced into the cell was 4.21 micromol/L. The relative standard deviation of the concentration of diclofenac sodium introduced into ten cells is 10%.     

毛细管电泳测定双氯芬酸钠制剂中的双氯芬酸钠

建立了制剂中双氯芬酸钠毛细管电泳高频电导分析法,并用于氯芬黄敏片及双氯芬酸钠肠溶片中双氯芬酸钠的测定。对电泳介质的种类、浓度以及操作电压和进样量等影响因素进行了优化。实验采用5mmol/L乳酸为缓冲溶液,22.0kV为分离电压,可在9min内实现对双氯芬酸钠的分离检测。在最佳实验条件下,双氯芬酸钠的线性范围为0.4~100μg/mL,检出限为0.1μg/mL。成功地检测了氯芬黄敏片及双氯芬酸钠肠溶片的有效成分双氯芬酸钠,回收率为92.4%~103.0%。     

Analysis of amino acids by capillary zone electrophoresis with electrochemical detection

The precapillary derivatization of 20 amino acids with naphthalene-2,3-dicarboxaldehyde (NDA) and CN(-) was investigated. All these derivatized amino acids could be oxidized on the carbon fiber microdisk bundle electrode except proline. Capillary zone electrophoresis with electrochemical detection was employed for the analysis of 19 amino acids. The optimum conditions of separation and detection were borate, pH 9.48, for the electrolyte, 18 kV for the separation voltage and 1.15 V versus a saturated calomel electrode for the detection potential. Limits of detection of concentration or mass for individual amino acids were between 1.7 x 10(-7) and 1.8 x 10(-6) mol/L or 84 and 893 amol (according to the signal-to-noise ratio of 3) for the injection voltage of 6 kV and injection time of 10 s. The relative standard deviations were between 0.80 and 2.3% for the migration times and 1.4 and 6.4% for the electrophoretic peak currents. From a mixture of 19 amino acids, 10 amino acids (Arg, Lys, Orn, Try, Ser, Ala, Gly, Cys, Glu, Asp) could be well separated. The other 9 amino acids appeared on three electrophoretic peaks. From the samples, in which the nine amino acids do not exist simultaneously, some of them could also be detected. The method was applied to the determination of amino acids in beer by the standard addition method. The recovery for the amino acids in beer was 91-109%.     

Determination of peroxides by capillary zone electrophoresis with amperometric detection

The combination of cathodic amperometric detection with capillary zone electrophoresis is demonstrated to be a versatile method for the quantification of organic and inorganic peroxides. A gold microelectrode, polarized at -600 mV against an Ag/AgCl reference electrode, is placed at the end of the capillary. Since the electroosmotic flow purges the detector electrode from oxygen, no degassing of the detector cell or the sample is necessary. With an injection volume of ca. 1 nl, hydrogen peroxide, peroxosulfate, peroxy alkanoic acids and the hydroperoxides of linoleic acid can be detected down to 10 micromol/l. Separation of the isomeric hydroperoxides of the unsaturated fatty acids is achieved by addition of beta-cyclodextrin to the electrolyte.     

毛细管电泳-电化学检测法测定饲料中的磺胺类药物

采用毛细管电泳-电化学检测法(CE-ED),对饲料中的6种磺胺类药物磺胺脒、磺胺二甲嘧啶、磺胺甲嘧啶、磺胺二甲氧嘧啶、磺胺嘧啶、磺胺甲恶唑进行了分离和测定。分别考察了工作电极电位、运行缓冲液的pH和浓度、分离电压和进样时间等实验参数对实验结果的影响。在优化的实验条件下,以直径300μm的碳圆盘电极为工作电极,检测电位为0.95 V(vs.SCE),在30 mmol/L硼砂-KH2PO4(pH7.6)的运行缓冲溶液中,6个分析物能够在16 min内实现很好的基线分离,被测物浓度与峰电流在3个数量级呈良好的线性,检出限(S/N=3)范围0.08～0.20μg/mL。该方法已应用于实际样品的分析。     

Determination of enkephalin peptides by nonaqueous capillary electrophoresis with electrochemical detection

Nonaqueous capillary electrophoresis with electrochemical detection (NACE-ED) was applied to the analysis of enkephalin peptides. The effect of different buffer compositions on the electrophoretic behavior of methionine enkephalin, leucine enkephalin, and [D-Ala2]-leucine enkephalin was studied. Separation of the protonated and the deprotonated peptides was obtained using ACN/methanol-based electrolyte systems. The electrochemical behavior of the enkephalins was studied by the capillary batch injection analysis technique. NACE-ED yielded well-defined signals in the oxidation mode only for the negatively charged analytes. The optimized BGE for the counterelectroosmotic separation consisted of 10 mM ammonium acetate in ACN/methanol (3:1 v/v). Using a platinum microdisk electrode set to an actual potential of +0.65 V detection limits in the submicromolar range were observed which are about one order of magnitude lower compared to UV detection. Problems concerning EOF instability and electrode fouling caused by water and other neutral sample impurities transported by the EOF can be avoided in the EOF-inverted mode using poly(ethylene glycol)-coated capillaries and an actual working electrode potential of +1.0 V. For the quantification of the enkephalins [D-Ala2]leucine enkephalin was used as internal standard. The practical utility for the determination of enkephalins in spiked plasma samples after SPE was demonstrated.     

毛细管电泳电化学检测法测定烟草中的多元酚

采用毛细管电泳电化学检测法同时测定了烟草中的多元酚,即芦丁、绿原酸,槲皮素和咖啡酸。考察了工作电极的氧化电位、运行缓冲溶液浓度和pH值,分离电压和进样时间对分离和检测的影响。在优化条件下,以300μm直径的碳圆盘电极为工作电极,检测电位为+0.9 V(vs.SCE),在50 mmol/L硼酸盐(pH 8.4)的运行缓冲液中,被测物浓度与峰电流在三个数量级范围内呈良好线性,检出限为2×10-7或5×10-7g/mL。方法有着良好的重现性,被测组分的迁移时间和峰高的相对标准偏差(RSDs)小于4%(n=7)。单次测定可在16 min内完成,已用于实际样品多元酚的测定,样品处理简单,无须预富集。     

Determination of biogenic amines by capillary zone electrophoresis with conductometric detection

A capillary zone electrophoresis (CZE) method with conductometric detection of biogenic amines (cadaverine, putrescine, agmatine, histamine, tryptamine and tyramine) is described. The optimised background electrolyte was the following: 15 mM histidine + 5 mM adipic acid + 1.5 mM sulphuric acid + 0.1 mM ethylenediaminotetraacetic acid + 0.1% hydroxyethylcellulose + 50% methanol. A clear separation of six biogenic amines from other components of acidic sample extract was achieved within 10 min. Method characteristics, i.e., linearity (0-100 micromol/ml), accuracy (recovery 86-107%), intra-assay repeatability (2-4%), and detection limit (2-5 micromol/l) were evaluated. Low laboriousness, sufficient sensitivity, speed of analysis, and low running cost are important attributes of this method. The developed method was successfully applied on the determination of biogenic amines in selected food samples.     

Determination of histamine by capillary zone electrophoresis with amperometric detection.

Capillary zone electrophoresis was employed for the determination of histamine using end-column amperometric detection with a carbon fiber microelectrode, at a constant potential. The optimum conditions of separation and detection were 10 mmol/L phosphate buffer, pH 5.6 for the buffer solution, 15 kV for the separation voltage, and 1.35 V (versus SCE) for the detection potential. The linear range was from 6.3 x 10(-7) to 1.5 x 1(-5) mol/L with the regression coefficient of 0.9997, and the detection limit was 4.0 x 10(-7) mol/L (S/N = 3). The proposed method was successfully applied to the direct determination of histamine in the beer samples without any sample clean-up procedures.     

Determination of diethylene glycol in toothpaste by capillary electrophoresis with electrochemical detection

Microchimica Acta - Diethylene glycol (DEG) can be determined in toothpaste via capillary electrophoresis at 16 kV using a fused silica capillary of 75 cm length and of...     

Determination of textile dyes by means of non-aqueous capillary electrophoresis with electrochemical detection

Eight textile dye compounds including five cationic dyes, namely, basic blue 41, basic blue 9, basic green 4, basic violet 16 and basic violet 3, and three anionic dyes, acid green 25, acid red 1 and acid blue 324, were separated and detected by non-aqueous capillary electrophoresis (NACE) with electrochemical detection. Simultaneous separations of acid and basic dyes were performed using an acetonitrile-based buffer. Particular attention was paid to the determination of basic textile dyes. The optimized electrophoresis buffer for the separation of basic dyes was a solvent mixture of acetonitrile/methanol (75:25, v/v) containing 1 M acetic acid and 10 mM sodium acetate. The limits of detection for the basic dyes were in the range of 0.1–0.7 μg mL⁻¹. An appropriate solid-phase extraction procedure was developed for the pre-treatment of aqueous samples with different matrices. This analytical approach was successfully applied to various water samples including river and lake water which were spiked with textile dyes.     

毛细管电泳电化学检测法同时测定三种氨基酸的电离常数

利用自制微圆盘铜电极,建立了一种毛细管电泳电化学检测同时测定色氨酸、丝氨酸和半胱氨酸pKα值的新方法。在不同pH条件下测定各氨基酸的有效淌度（μeff）,利用Origin软件对μeff-[H^＋]按理论关系式进行非线性拟合,得到其pKα值。该方法简便、快速,测定值与文献值符合良好。     

Determination of ionization constants of saccharides by capillary zone electrophoresis with amperometric detection

Summary A method based on a linear model enabling the efficient determination of the ionization constants (K _a) of saccharides by capillary zone electrophoresis with amperometric detection has been demonstrated. TheK _a values obtained from the plots of the reciprocal effective mobility against the inverse concentration of sodium hydroxide were in agreement with literature values.     

Determination of sulfadiazine and sulfamethoxazole by capillary electrophoresis with end-column electrochemical detection.

Capillary electrophoresis (CE) with end-column electrochemical detection (EC) of sulfadiazine (SDZ) and sulfamethoxazole (SMZ) is described. Under the optimum conditions, SDZ and SMZ were separated satisfactorily, and a highly sensitive and stable response was obtained at a potential of 1.1 V versus Ag/AgCl. Optimized end-column detection provides detection limits as low as 0.1 microM for both compounds, which corresponds to 0.024 and 0.021 fmol with peak efficiencies of 394,000 and 335,000 theoretical plates for SDZ and SMZ, respectively. The calibration graph was linear over three order of magnitude. The relative standard deviations (n = 12) of peak currents and migration times were 2.3 and 2.7%, and 0.8 and 1.3%, respectively, for the two compounds. The proposed method was applied to the analysis of tablets and human urine samples with satisfactory results.     

Determination of benzhexol hydrochloride by capillary zone electrophoresis with an end-column electrochemiluminescence detection

A capillary zone electrophoresis with end-column electrochemiluminescence (ECL) detector was described for the determination of benzhexol hydrochloride. The detection was based on the tris(2,2′-bypyridine)ruthenium(II) [Ru(bpy)₃²⁺] ECL reaction with the analyte. Electrophoresis was performed using a 25 μm i.d. uncoated capillary. 10 mM sodium phosphate buffer (pH=8.0) was used as the running buffer. The solution in the detection cell was 80 mM sodium phosphate (pH=8.0) and 5 mM Ru(bpy)₃²⁺. A linear calibration curve of three-orders of magnitude was obtained (with a correlation coefficient of >0.999) from 1.0×10⁻⁸ to 1.0×10⁻⁵ M and the limit of detection was 6.7×10⁻⁹ M (S/N=3). This just provides an easy and sensitive method to determine the active ingredient in pharmaceutical formulations.     

Determination of idarubicin in human urine by capillary zone electrophoresis with amperometric detection

A simple, reliable and reproducible method, based on capillary zone electrophoresis with amperometric detection, has been developed for the determination of idarubicin in human urine. A carbon disk electrode was used as working electrode. The optimal conditions of separation and detection were pH 5.6 phosphate buffer (0.20 mol/L), 22 kV for the separation voltage and 1.00 V (vs. Ag/AgCl, 3 mol/L KCl) for the detection potential. The linear range was from 4.0 x 10(-7) to 2.0 x 10(-5) mol/L with a regression coefficient of 0.9986, and the detection limit was 8.0 x 10(-8) mol/L. The method was directly applied to the determination of idarubicin in spiked human urine without any other sample pretreatment except filtration, and the assay results were satisfactory.     

Determination of aluminum in serum by capillary zone electrophoresis with laser-induced fluorescence detection

Summary A novel method of separating and detecting trace aluminum by capillary zone electrophoresis is described. Aluminum is reacted with lumogallion [4-chloro-3-(2,4-dihydroxyphenylazo)-2-hydroxybenzen-1-sulphonic acid] so that the complex can be selectively and sensitively detected by a laser-induced fluorescence detector after capillary electrophoretic separation. Using the proposed method, limits of detection in the sub parts per billion range are achieved. The technique is applied to the determination of aluminum in human serum.     

Determination of idarubicin in human urine by capillary zone electrophoresis with amperometric detection

A simple, reliable and reproducible method, based on capillary zone electrophoresis with amperometric detection, has been developed for the determination of idarubicin in human urine. A carbon disk electrode was used as working electrode. The optimal conditions of separation and detection were pH 5.6 phosphate buffer ¶(0.20 mol/L), 22 kV for the separation voltage and 1.00 V (vs. Ag/AgCl, 3 mol/L KCl) for the detection potential. The linear range was from 4.0 × 10^–7 to 2.0 × 10^–5 mol/L with a regression coefficient of 0.9986, and the detection limit was 8.0 × 10^–8 mol/L. The method was directly applied to the determination of idarubicin in spiked human urine without any other sample pretreatment except filtration, and the assay results were satisfactory.     

Assay of amino acids in individual human lymphocytes by capillary zone electrophoresis with electrochemical detection

Amino acids in individual human lymphocytes were determined by capillary zone electrophoresis with electrochemical detection (ED) at a carbon fiber bundle electrode after on-column derivatization with naphthalene-2,3-dicarboxaldehyde (NDA) and CN⁻. In order to inject cells easily, a cell injector was designed. In this method, a single human lymphocyte and then the lysing/derivatizing buffer were electrokinetically injected into the front end of the separation capillary as a chamber to lyse the lymphocyte and derivatize amino acids in the cell. Four amino acids (serine (Ser), alanine (Ala), taurine (Tau), and glycine (Gly)) in single human lymphocytes have been identified. Quantitation has been accomplished through the use of calibration curves.     

Quantitative determination of glutathione in single human erythrocytes by capillary zone electrophoresis with electrochemical detection

Glutathione (GSH) in single human erythrocytes is determined by capillary zone electrophoresis with end-column amperometric detection at a gold/mercury amalgam microelectrode. A capillary of 10 microm inner diameter is suitable for determination of GSH in an individual erythrocyte with a good signal-to-noise ratio. The limit of detection is 1 x 10(-7) mol/L or 26 amol and the linear dynamic range is 2 x 10(-7) to 2 X 10(-5) mol/L for the capillary. In this method, the calibration line is obtained with a capillary adsorbed before a certain amount of hemoglobin can be used for the quantification of GSH in the external standardization. The whole cell injection and the lack of necessity of a derivatization reaction lead to more accurate and precise results, which are closer to the macroscopic values of glutathione in human red blood cell (i.e., hemolysate) than those determined by indirect laser-induced fluorescence detection.