Nonaqueous capillary electrophoresis of dextromethorphan and its metabolites

This study deals with the nonaqueous capillary electrophoretic separation of dextromethorphan and its metabolites using a methanolic background electrolyte. The optimization of separation conditions was performed in terms of the resolution of dextromethorphan and dextrorphan and the effect of separation temperature, voltage, and the characteristics of the background electrolyte were studied. Complete separation of all analytes was achieved in 40 mM ammonium acetate dissolved in methanol. Hydrodynamic injection was performed at 3 kPa for 4 s. The separation voltage was 20 kV accompanied by a low electric current. The ultraviolet detection was performed at 214 nm, the temperature of the capillary was 25°C. These conditions enabled the separation of four analytes plus the internal standard within 9 min. Further, the developed method was validated in terms of linearity, sensitivity, and repeatability. Rat liver perfusate samples were subjected to the nonaqueous capillary electrophoretic method to illustrate its applicability.     

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。     

毛细管区带电泳法测定消毒剂中三氯新

建立了消毒剂中三氯新的毛细管电泳分析方法。探讨了缓冲介质和电泳参数对三氯新测定的影响。以15mmol/LNa2HPO4(pH6.0)-乙腈(V(Na2HPO4)∶V(乙腈)=50∶50)为电泳缓冲液,三氯新在12kV电压下电泳,于254nm检测波长处测定,6min可以完成分析。本方法的检出限为0.04mg/L,线性范围0.04～2.00mg/mL(r=0.997),加标回收率在90.9%～108.2%范围内,测定值的相对标准偏差分别为峰高7.7%,迁移时间5.5%。将本法与高效液相色谱法进行比较,样品测定结果的相对误差小于10%。将所建立的方法已用于消毒剂样品中三氯新的测定。     

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。     

区带毛细管电泳法分离测定洋金花中莨菪烷类生物碱

采用区带毛细管电泳法分离测定洋金花中3种莨菪烷类生物碱—阿托品、山莨菪碱和东莨菪碱。以57 cm×50μm熔融石英毛细管为分离通道,工作电压25 kV,温度25℃,200 mmol/L Tris-H3PO4(pH=8.3)为背景电解质。经优化分离条件,3种莨菪烷类生物碱达到基线分离,此方法快速、简便,可作为中药材洋金花中有效成分分离的方法和质量控制方法。     

Determination of egg white lysozyme by on-line coupled capillary isotachophoresis with capillary zone electrophoresis

An on-line coupled capillary isotachophoresis - capillary zone electrophoresis method for the determination of lysozyme in selected food products is described. The optimized electrolyte system consisted of 10 mM NH(4)OH + 20 mM acetic acid (leading electrolyte), 5 mM epsilon -aminocaproic acid +5 mM acetic acid (terminating electrolyte), and 20 mM epsilon -aminocaproic acid +5 mM acetic acid +0.1% m/v hydroxypropylmethylcellulose (background electrolyte). A clear separation of lysozyme from other components of acidic sample extract was achieved within 15 min. Method characteristics, i.e., linearity (0-50 micrograms/mL), accuracy (recovery 96+/-5%), intra-assay (3.8%), quantification limit (1 microgram/ml), and detection limit (0.25 microgram/mL) were determined. Low laboriousness, sufficient sensitivity and low running costs are important attributes of this method. The developed method is suitable for the quantification of the egg content in egg pasta.     

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).      

毛细管区带电泳法间接测定红细胞中的主要无机阳离子

建立了间接测定红细胞中主要无机阳离子的毛细管区带电泳方法, 考察了背景溶液pH、咪唑和酒石酸浓度等对无机离子分离效果及峰面积的影响. 以10 mmol/L咪唑-4 mmol/L酒石酸(pH 5.5)为背景, 在15 kV、214 nm的条件下, 对红细胞中K 、Mg2 、Ca2 和Zn2 进行了定性、定量分析, 回收率在96%～104%之间, 迁移时间和峰面积的相对标准偏差分别低于0.76%和2.8%(日内), 0.85%和3.7%(日间). 所建方法有望成为一种测定细胞内离子含量的辅助方法.     

Simultaneous determination of tetracyclines in poultry muscle by capillary zone electrophoresis

A capillary zone electrophoresis method with UV detection was developed for the simultaneous detection and quantification of three tetracyclines in chicken meat samples: tetracycline (TC), oxytetracycline (OTC) and doxycycline (DOC). The separation conditions were: a running buffer containing 30 mM sodium phosphate, 2 mM EDTA disodium salt and 2.5% 2-propanol, pH 12.0, a 5 s hydrodynamic injection and a 14 kV separation voltage. Two different clean-up methodologies were employed: solid-phase extraction with C₁₈ cartridges and ion exchange with Amberlite XAD7 resin. Analytes were detected at 360 nm in less than 12 min. LODs ranged from 61 μg kg⁻¹ for OTC to 68 μg kg⁻¹ for DOC with C₁₈ cartridges, and 81 μg kg⁻¹ for DOC to 89 μg kg⁻¹ for TC with Amberlite XAD7 resin. The recoveries for TC, OTC and DOC obtained by both methods were between 85 and 95%, and the peak area repeatability for all of the samples was below 5% in all cases. Twenty-four samples of commercial chicken drumsticks were examined with both clean-up methodologies. In nine cases (37.5%) TC was detected, in a range from 197.8 to 2564.3 μg kg⁻¹, and in seven cases (29.2%) OTC was detected in a range from 83.0 to 2049.3 μg kg⁻¹. DOC was not detected in any of the tested samples. This method would be useful for the routine monitoring of TCs residues in poultry muscle.     

Determination of fosfomycin in pus by capillary zone electrophoresis

A method is described for the determination of fosfomycin in pus by capillary zone electrophoresis with reversed electroosmotic flow, and indirect UV absorbance detection. Sample pre-treatment is limited to removal of proteins and cell debris by adding the double volume of methanol, followed by vortexing for few seconds, and centrifugation at 15,000 x g for 2 min. The supernatant is directly injected into the instrument. Fosfomycin is separated from sample constituents with a background electrolyte at pH 7.25 (25 mM benzoate buffer with 0.5 mM hexadecyltrimethylammonium bromide added, adjusted to pH with tris(hydroxymethyl)-aminomethane (TRIS)). Separation is carried out in a capillary with 50 microm I.D., 64.5 cm total length, 56.0 cm to the detector, at 25 degrees C with -25 kV voltage applied. Due to the low absorbance of the analyte, indirect UV detection was performed at 254 nm using a bubble cell capillary. Sample was injected by pressure (450 mbar s). Repeatability for fosfomycin in spiked pus (from 8 or 10 consecutive injections of three different series at concentrations of 100 microg/mL of the antibiotic) was between 2.4 and 8.2% relative standard deviation (RSD). Accuracy (expressed as recovery of fosfomycin determined by three independent analysis at 10, 100 and 300 microg/mL fosfomycin added to plain pus) was between 75 and 102%. Intermediate reproducibility (n = 9 at three different days) was between 2 and 12% RSD. Limit of detection and limit of quantitation were 4.5 and 15 microg/mL, respectively. The concentration of fosfomycin in pus of patients treated with the antibiotic ranged up to 240 microg/mL. The concentration of other anionic pus constituents identified beside chloride (acetate, succinate, lactate, phosphate) ranged between 20 and 7800 microg/mL.     

Separation and simultaneous determination of quinolone antibiotics by capillary zone electrophoresis

Summary The potential of capillary zone electrophoresis has been investigated for the separation and quantitative determination of some quinolone antibiotics. The influence of different conditions, such as the nature and concentration of the electrophoretic electrolyte, on migration time, peak symmetry, efficiency and resolution was studied. A buffer consisting of 100mm HEPES adjusted to pH 8.5 containing 10% (v/v) acetonitrile was found to furnish a very efficient and stable electrophoretic system for the separation of exoxacin, ciprofloxacin, ofloxacin, oxolinic acid, nalidixic acid and pipemedic acid. A linear relationship between concentration and peak area for each compound was obtained in the concentration range 0.25–40 μg mL⁻¹; detection limits were approximately 0.25 ng mL⁻¹. It was demonstrated that the method can be used for the simultaneous determination of these six antibiotics in serum and urine samples.     

Determination of the ionization constants of weak electrolytes by capillary zone electrophoresis

Capillary zone electrophoresis in untreated fused silica capillaries has proved suitable for the determination of the ionization constants of weak electrolytes. Several fundamental equations relating the electrophoretic mobilities of ionized solutes to hydronium ion concentrations in the running electrolyte have been verified experimentally. The observed dependence of the electrophoretic mobilities of weak bases and ampholytes on the pH of the electrolyte showed good agreement with predicted behavior. The pK_a values calculated from electrophoretic mobility data obtained by capillary zone electrophoresis were reasonably close to those reported in the literature.     

Direct determination of bromide ions in seawater by capillary zone electrophoresis using polyethyleneimine-coated capillaries

A rapid and simple capillary electrophoretic method was developed for the direct determination of bromide ion in seawater. We have found an effective method, based on the use of polyethyleneimine-coated capillaries and the addition of sodium chloride to the background electrolyte. The use of coated capillaries with a cationic polymer changes the direction of the electroosmotic flow in the capillary, which favors the migration speed of the bromide ion and enables the use of low salt concentrations in the separation electrolyte. Bromide ion in seawater can be determined within 2 min using this system and 20 mmol L^-1 NaCl-containing separation electrolyte. The detection limit for the bromide ion was 0.45 g ml^-1. The method was applied to the determination of bromide ion in seawater samples collected from the Bosphorus and the Black Sea. Bromide contents in samples from 0 to 72 m depths varied between 33.2 and 72.8 mg L^-1 with a mean 3.0% RSD.     

Determination of Substance P by capillary zone electrophoresis in rat brain

In the complex neuronal network, chemical messengers like neuropeptides play a key role in signaling. To understand the mechanism of signaling, it is necessary to analyze the levels of neuropeptides from biological sources, which is important for neuroscience research. In the present work, a detailed investigation of the capillary zone electrophoresis (CZE) method was carried out to detect and quantify Substance P (SP), a bioactive neuropeptide, in rat brain tissues. The method involves specifically, a combination of solid phase extraction and immunoprecipitation prior to the CZE quantification. In this procedure, antibodies are used to capture the analyte of interest before the separation by CZE. Different separation parameters like buffer type, concentration, pH and applied voltage were the steps taken to study and achieve high efficiency CZE separation. CZE analysis was performed in an untreated fused-silica capillary column (35 cm×75 μm i.d.) and 185 nm wavelength using 100 mM phosphate buffer (pH 2.5) as a separation buffer. Electrophoresis in acidic mode and successive washing procedures solved the adsorption problem. The method provides a rapid analysis time of less than 15 min with 3.91% of RSD. Simultaneously, SP was quantified by Matrix Assisted Laser Desorption Ionization-Time of Flight-Mass Spectrometry (MALDI-TOF-MS) and compared with CZE data. Starting from milligram amounts of brain tissue, the method allowed the detection of low picomole amounts of SP and the combined use of CZE and MALDI-TOF-MS was a success in quantification in this study.     

Determination of brominated phenols in water samples by on-line coupled isotachophoresis with capillary zone electrophoresis

A method for determination of nine brominated phenols as environmental risk compounds was developed by on-line coupled capillary isotachophoresis and capillary zone electrophoresis (ITP–CZE). For ITP step, 1 × 10⁻² mol L⁻¹ hydrochloric acid with 3 × 10⁻² mol L⁻¹ ammediol pH 9.1 was used as the leading electrolyte, and 3 × 10⁻² mol L⁻¹ β-alanine with 2 × 10⁻² mol L⁻¹ sodium hydroxide pH 10.05 was used as the terminating electrolyte. As the background electrolyte for CZE separation, 2.5 × 10⁻² mol L⁻¹ β-alanine with 2.5 × 10⁻² mol L⁻¹ lysine pH 9.6 was used. All electrolytes contained 0.05% or 0.1% (m/v) hydroxyethylcellulose to suppress the electroosmotic flow. UV detection at wavelength 220 nm was used. Detection limits in order of tens of nmol L⁻¹ were achieved. Good repeatability of migration times (less than 0.33% RSD) and good repeatability of peak areas (less than 7.19% RSD) at concentration level 5 × 10⁻⁸ mol L⁻¹ were observed. Developed ITP–CZE method was applied to determination of brominated phenols in spiked tap and river water samples.     

Determination of fenfluramine enantiomers in pharmaceutical formulations by capillary zone electrophoresis

Summary Capillary zone electrophoresis has been used for the enantiomeric separation of racemic ortho-fenfluramine and meta-fenfluramine employing a phosphate buffer at pH 2.5 added with cyclodextrins. The cyclodextrin type and concentration strongly influenced the chiral resolution. The uncharged β-cyclodextrin polymer gave enantiomeric resolution of both ortho and meta isomers, while γ-cyclodextrin was a good chiral selector for only ortho-fenfluramine; heptakis-2,3,6-tri-O-methyl-β-cyclodextrin permitted base line separation of meta-fenfluramine enantiomers but only partial resolution of racemic ortho-fenfluramine. The optimized electrophoretic method was applied to the quantitative analysis of 1-meta-fenfluramine (minor component in the mixture) and d-meta-fenfluramine in a commercial pharmaceutical formulation. Good reproducibility for migration time and corrected peak areas (R.S.D. <0.8 % and <1.2 %, respectively) was achieved and the presence of the minor component of the mixture was found to be in accord to previous determinations performed by other analytical methods.     

Simultaneous determination of uranium carbide dissolution products by capillary zone electrophoresis

Separation and simultaneous determination of a number of organic acid anions (oxalate, mellitate, trimellitate and benzoate) and U(VI) with direct UV detection is developed for analysis of uranium carbide (UC) dissolution products by capillary zone electrophoresis (CZE). Reverse polarity mode is used. It is found that complex formation of U(VI) with carbonate, used as a carrier electrolyte, allows U(VI) to be determined, as negatively charged species, in a single run with organic acid anions. Some parameters such as pH value, composition of electrolyte and detection wavelength are optimized. Under the chosen conditions (carbonate buffer (ionic strength of 100 mM), pH 9.8, 0.15 mM tetradecyltrimethylammonium bromide (TTAB)) a complete separation is achieved. Calibration plots are linear in two ranges of concentration for U(VI) (∼1 × 10⁻⁵ to 1 × 10⁻³), mellitate and trimellitate (∼5 × 10⁻⁶ to 5 × 10⁻⁴), and about one range (∼1 × 10⁻⁴ to 5 × 10⁻³) for oxalate and benzoate. Accuracy of the procedure is checked by the “added-found” method in standard mixture solutions. Relative standard deviation is within the range of 2–10% and the recovery is in the range of 90–110%. This method is applied for the analysis of real UC dissolution samples.     

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.     

Determination of fenfluramine enantiomers in pharmaceutical formulations by capillary zone electrophoresis

Summary Capillary zone electrophoresis has been used for the enantiomeric separation of racemic ortho-fenfluramine and meta-fenfluramine employing a phosphate buffer at pH 2.5 added with cyclodextrins. The cyclodextrin type and concentration strongly influenced the chiral resolution. The uncharged β-cyclodextrin polymer gave enantiomeric resolution of both ortho and meta isomers, while γ-cyclodextrin was a good chiral selector for only ortho-fenfluramine; heptakis-2,3,6-tri-O-methyl-β-cyclodextrin permitted base line separation of meta-fenfluramine enantiomers but only partial resolution of racemic ortho-fenfluramine. The optimized electrophoretic method was applied to the quantitative analysis of 1-meta-fenfluramine (minor component in the mixture) and d-meta-fenfluramine in a commercial pharmaceutical formulation. Good reproducibility for migration time and corrected peak areas (R.S.D. <0.8% and <1.2%, respectively) was achieved and the presence of the minor component of the mixture was found to be in accord to previous determinations performed by other analytical methods.