Capillary electrophoresis as a versatile tool for the bioanalysis of drugs--a review

This review article presents an overview of current research on the use of capillary electrophoretic techniques for the analysis of drugs in biological matrices. The principles of capillary electrophoresis and its various separation and detection modes are briefly discussed. Sample pretreatment methods which have been used for clean-up and concentration are discussed. Finally, an extensive overview of bioanalytical applications is presented. The bioanalyses of more than 200 drugs have been summarised, including the applied sample pretreatment methods and the achieved detection limits.     

Capillary zone electrophoresis determination of meropenem in biological media using a high sensitivity cell

A capillary electrophoresis method with a high sensitivity cell (Z-cell) has been developed for the determination of meropenem in aqueous solution and in biological media (urine, plasma). Water samples were analysed using two calibration curves of meropenem with standard capillary and a capillary with a high sensitivity cell. In urine, the samples were only diluted in buffer and were injected without any further sample preparation. For the analysis of plasma samples, a calibration curve was utilized covering the meropenem concentration range of 0.5–200 μg/ml. The detection limit and the relative standard deviation of the migration times and of the peak areas were determined.     

Capillary electrophoresis and high-performance anion exchange chromatography for monitoring caseinoglycomacropeptide sialylation

Capillary zone electrophoresis was applied to separate caseinoglycomacropeptide glycoforms and characterize microheterogeneity of the glycopeptide. Particular attention was paid to the sialic acid content in caseinoglycomacropeptide obtained through different manufacturing processes. A chemometric approach was used to simultaneously study effects of acid concentration, hydrolysis time and temperature on sialic acid release from caseinoglycomacropeptide. Hydrolysis conditions that maximize sialic acid release were chosen. Sialic acid was determined using high performance anion exchange chromatography coupled with pulsed amperometric detection. Results were compared to those obtained by alternative techniques, such as colorimetric and enzymatic methods.     

Capillary electrophoresis as a metabolomic tool in antioxidant therapy studies

The development of an approach by which two CE methods operating with opposite polarities and orthogonal capillary electrophoretic separation modes (method 1: normal polarity cyclodextrin modified MEKC (CD-MEKC) and method 2: reversed polarity CZE) for the sequential application to urinary samples from a type I diabetes metabolomics investigation is discussed. During method development, problematic MEKC profile drift issues arising from the high glucose content of the diabetic animal urine samples required some electrolyte modifications involving the use of hexafluoroisopropanol (HFIP) to circumvent the drift. Data derived from both methods were subsequently subjected to alignment, normalization and multi-dimensional scaling (MDS) procedures. In such a way, classification of samples derived from control and diabetic animals receiving a placebo from those receiving an antioxidant nutraceutical, was successfully demonstrated. Such a strategy is a cost effective and comprehensive metabolomics tool useful for describing UV absorbing metabolite disease-related changes in nutra/pharma-ceutical studies.     

High-throughput multi-analyte screening for renal disease using capillary electrophoresis

End-state renal disease (ESRD) affects 300 000 people in the United States each year. A large percentage of these individuals (20%) die within the first year after diagnosis. Current methods of determining renal function rely on the measurement of a single marker using slow and frequently non-specific colorimetric methods. In this report, capillary zone electrophoresis was used to perform a multi-analyte assay for markers of renal function in urine. This method tested for creatinine (Cr), creatine (Cn), uric acid (UA), and p-aminohippuric acid (PAH) levels. The limits of detection (S/N=3) were found to be 5 μM for Cr, 0.75 μM for Cn, and 1.5 μM for UA and PAH. Linear ranges were determined to be 5–500 μM for Cr, 0.75–500 μM for Cn, and 1.5–250 μM for UA and PAH. These ranges included the expected concentrations of the markers in human urine after 50-fold dilution. This screening method proved to be a simple and fast way to perform a high throughput analysis for multiple renal function indicators.     

Capillary electrophoresis as a metabolomics tool for non-targeted fingerprinting of biological samples

Metabolomics, understood as a data driven strategy trying to find markers of a situation under study without a priori hypothesis, has rapidly caught the attention and evolved from the simple pattern recognition strategy, which was a great innovation at its origins, to the interest for the final identification of markers responsible for class separation, i.e., from data to knowledge. Due to differences in physico-chemical properties and concentrations of the metabolites, but also due to differences in matrix properties, cross-platform approaches are proving to increase the capability of information. Once more techniques do not compete. This is the scene where capillary electrophoresis (CE) has its niche to provide information mainly on polar or ionic compounds in biological fluids. General advantages and disadvantages of CE for sample fingerprinting will be discussed and methods will be classified depending on the detection system (UV or MS) as this strongly affects all the conditions. Recent developments will be presented in different biological fluids, although urine is without a doubt the preferred sample for CE analysis.     

ROC曲线评价毛细管区带电泳用于α地中海贫血筛查的临床价值

目的探讨血红蛋白毛细管区带电泳用于α地中海贫血筛查的临床价值,确定血红蛋白A2（HemoglobinA2,HbA2）用于α地中海贫血诊断的截断值。方法收集66例d地中海贫血病例α地中海贫血组）和86例健康对照（正常对照组）。采集各组研究对象的静脉血进行血红蛋白毛细管区带电泳和α地中海贫血基因检测,通过建立受试者工作特征曲线（ROC曲线）对HbA2在α地中海贫血诊断中的统计学指标进行综合评价,并确定HbA2用于α地中海贫血诊断的截断值;统计工具采用SPSS17．0统计软件。结果d地中海贫血组和正常对照组的毛细管区带电泳的HbA2检测结果分别为（2．33±0．22）％和（2．65±0．29）％,α地中海贫血组明显低于正常对照组,差异有统计学意义（P〈0．01）。HbA2用于诊断α地中海贫血的ROC曲线下面积（AUC）为0．804（SE：0．035,95％CI：0．736～0．872）,诊断价值具有统计学意义俨〈0．011;HbA2用于仪地中海贫血诊断的截断值为2．55％,对应的诊断灵敏度和特异度分别为60．5％和89．4％。结论血红蛋白毛细管区带电泳检测HbA2用于α地中海贫血筛查是目前较好的方法,具有较高的临床价值。     

毛细管电泳用于神经氨酸酶抑制剂筛选方法研究D

目的 建立适用于复杂体系的神经氨酸酶抑制剂毛细管电泳筛选方法。方法 以神经氨酸酶为靶点,以2￠-(4-甲基伞形酮-a-N-乙酰神经氨酸)为底物,建立神经氨酸酶抑制剂的毛细管电泳筛选方法,并将该方法用于海洋药物可口革囊星虫粗提物的活性筛选。结果 以10 mmol.L-1 pH 10.0的硼砂为背景电解质,酶促反应底物与产物在4.5分钟内基线分离。酶促反应在含4 mmol.L-1 CaCl2的pH 3.5的磷酸体系中,37℃水浴中酶与底物孵育15min,产物有稳定的较大的生成量。扎那米韦阳性对照验证结果表明,该方法可用于神经氨酸酶抑制剂筛选。对源于可口革囊星虫的11个粗提物筛选结果显示,7个粗提物对神经氨酸酶有抑制活性。结论 系统优化了毛细管电泳分离分析方法及神经氨酸酶反应体系,建立的模型可用于复杂体系中抗流感病毒药物神经氨酸酶抑制剂的筛选。     

Advances in capillary electrophoresis and the implications for drug discovery

Introduction: Many screening platforms are prone to assay interferences that can be avoided by directly measuring the target or enzymatic product. Capillary electrophoresis (CE) and microchip electrophoresis (MCE) have been applied in a variety of formats to drug discovery. CE provides direct detection of the product allowing for the identification of some forms of assay interference. The high efficiency, rapid separations, and low volume requirements make CE amenable to drug discovery.

Areas covered: This article describes advances in capillary electrophoresis throughput, sample introduction, and target assays as they pertain to drug discovery and screening. Instrumental advances discussed include integrated droplet microfluidics platforms and multiplexed arrays. Applications of CE to assays of diverse drug discovery targets, including enzymes and affinity interactions are also described.

Expert opinion: Current screening with CE does not fully take advantage of the throughputs or low sample volumes possible with CE and is most suitable as a secondary screening method or for screens that are inaccessible with more common platforms. With further development, droplet microfluidics coupled to MCE could take advantage of the low sample requirements by performing assays on the nanoliter scale at high throughput.     

Capillary electrophoresis with indirect UV detection for the determination of stabilizers and citrates present in human albumin solutions

Sodium caprylate and N-acetyltryptophan are the most frequently used stabilizers that protect the albumin from aggregation or heat induced denaturation. In turn citrates – excipients remaining after fractionation process – can be treated as by-product favoring leaching aluminum out of glass containers whilst albumin solution is stored. With ionic nature these substances have all the markings of a subject for capillary electrophoresis analysis. Thus CE methods were proposed as new approach for quality control of human albumin solution in terms of determination of stabilizers and citrates residue.     

The quantitative determination of several inhibitors of the angiotensin-converting enzyme by CE

Capillary electrophoresis (CE) was applied to the study of several inhibitors of the angiotensin-converting enzyme. Separation of the compounds was performed by means of two phosphate buffers (each 100 mM) at pH 7.0 and 6.25, respectively [S. Hillaert, W. Van den Bossche, J. Chromatogr. A, 895 (2000) 33–42.]. Due to the highest selectivity of the first mentioned running buffer, the same system has been applied for the quantification of enalapril, lisinopril, quinapril, fosinopril, perindopril and benazepril in their corresponding pharmaceutical formulation. Especially, the possibility of simultaneous identification and quantification of the active ingredient in the finished product is very attractive. Excipients do not adversely affect the results. This paper deals with the validation of some parameters of the quantitative analysis: linearity, precision, accuracy and robustness.     

阿托品光学异构体的毛细管电泳法拆分研究

摘 要 目的：考察阿托品光学异构体的毛细管电泳拆分方法。方法: 采用毛细管电泳法,弹性石英毛细管柱（60 cm×75 μm,有效长度40 cm）,磷酸盐缓冲液浓度：30 mmol·L^-1,重力进样高度差10 cm,进样时间：5 s,检测波长：225 nm。分别对手性拆分剂种类及浓度、缓冲溶液的pH、运行电压、有机溶剂等进行考察,优选出最佳拆分条件。 结果: 阿托品光学异构体最佳拆分条件为：缓冲液pH为7.0,磺酸化-β-环糊精聚合物（S-β-CDP）浓度为10 mg·mL^-1,电压为12 kV。结论:本方法简便、快速,能实现对阿托品光学异构体的拆分。     

Capillary electrophoresis: a new analytical tool for forensic toxicologists

In capillary electrophoresis, electrophoretic or electrokinetic separations are carried out in tiny capillaries at high voltages (10-30 kV), thus achieving high efficiency (N > 105), resolution power, and mass sensitivity (down to 10(-18)-10(-20) moles). The main characteristics of capillary electrophoresis are versatility of application (from inorganic ions to large DNA fragments), use of different separation modes with different selectivity, low demands on sample volume, negligible running costs, possibility of interfacing with different detection systems including mass spectrometry, and the ruggedness and simplicity of the instrumentation. Capillary electrophoresis applications in the forensic sciences are now rapidly growing, particularly in forensic toxicology. The present paper briefly describes the basic principles of capillary electrophoresis and presents a selected review of its main applications to the analysis of illicit/controlled drugs in biologic samples. An original analytical approach to the determination of carbohydrate deficient transferrin, a new marker of chronic alcohol abuse, based on capillary electrophoresis is also described. It is concluded that the peculiar separation mechanisms and the high complementarity of capillary electrophoresis to chromatography make it a new powerful tool of investigation in the hands of forensic toxicologists.     

Determination of cationic surfactants as the preservatives in an oral solution and a cosmetic product by capillary electrophoresis

In this study, a capillary electrophoresis method was developed for the determination of cationic surfactants, benzethonium and cetylpyridinium ions, which are commonly used as preservatives in various pharmaceutical and cosmetic products. Determination was performed in a fused-silica capillary using a mixed 75 mmol/L phosphoric acid and 50% acetonitrile electrolyte at pH 2.5. Analysis of benzethonium and cetylpyridinium ions was achieved in around 5 min. Repeatability in migration times (R.S.D.%) for benzethonium and cetylpyridinium ions were 0.3. The calibration curves were linear from 0.0125 to 0.400 mmol/L for benzethonium ions and from 0.025 to 0.400 mmol/L for cetylpyridinium ions. The minimum detection limits (signal-to-noise ratio = 3) are 1.47 and 4.30 μg/mL for benzethonium and cetylpyridinium ions, respectively. The method was applied to the analysis of benzethonium ion in a cosmetic product and cetylpyridinium ion in a mouthwash.     

Development of a capillary electrophoresis method for the determination of orphenadrine citrate in tablets in the presence of paracetamol

A validated method using capillary electrophoresis was developed, for the determination of orphenadrine citrate in its tablet formulations, in the presence of paracetamol. The method employs a running buffer of 30 mM pentane sulfonate sodium, dissolved in 20 mM MOPS buffer pH 7.7. Samples were injected using hydrodynamic sample injection mode (25 mbar, for 25 s), using positive polarity of 25 kV, at a constant temperature of 30 °C. Samples of orphenadrine citrate alone or in mixture solutions with paracetamol were exposed to various degradation conditions, and were electrophoresed using the recommended condition. The method was found to be specific, linear (r² = 0.994), precise, accurate, and robust, with an LOQ of 0.02 mg/mL. The proposed method was successfully applied for measurement of the percentage per label of orphenadrine citrate in commercially available tablets.     

Characterization of quinidine 3-hydroxylation as a probe for the CYP 3A enzyme using a novel capillary electrophoresis technique

Capillary electrophoresis (CE) with a direct injection technique was used to characterize the formation of (3S)-3-hydroxyquinidine (3-OHQ) as a probe for the CYP 3A isoenzymes in rat liver microsomes. Detection was performed either in the absorbance mode or by employing laser-induced fluorescence (LIF) detection. Michaelis–Menten parameters (mean values±S.D.) K_m and V_max for the formation of 3-OHQ from the probe drug quinidine sulfate (QS) in rat liver microsomes were 37±4.6 μg/ml (47.1±5.9 μM) and 321±4 ng/mg/h (942±11.7 pmol/mg/h), respectively. Inhibition studies were performed to evaluate the specificity of 3-OHQ as a probe for the CYP 3A enzyme. Ketoconazole and fluconazole were found to be inhibitors of 3-OHQ formation and exhibited K_i values of 0.19 and 20.1 μM, respectively. Inhibition with the weak inhibitor, erythromycin could only be estimated using LIF detection due to lack of sensitivity in the absorbance mode. The formation of 3-OHQ in rat liver microsomes can be used as a model for the screening of the CYP 3A enzyme. Direct injection, ensures faster analysis time due to the lack of sample preparation and the low volume capabilities of the technique makes it attractive for the screening of a large number of compounds.     

苯甲胺作探针的毛细管电泳-间接紫外检测法检测注射用盐酸头孢吡肟中的N-甲基吡咯烷

建立了毛细管电泳 -间接紫外检测法检测注射用盐酸头孢吡肟中的 N-甲基吡咯烷。毛细管电泳条件 :采用熔融石英毛细管柱 (5 0μm i.d× 6 4 .5 cm,有效柱长为 5 6 cm ) ,以含 0 .0 1mol/ L苯甲胺和 0 .0 2 5 mol/ L甲酸的溶液 (p H3.6 )为背景电解质 ,电压为30 k V,柱温为 2 5℃ ,在 2 14 nm波长处间接检测。选用二乙胺作内标以提高方法的精密度。分离过程中在毛细管的进口处加 2 5 mbar的压力可得到稳定的基线。在选择性、线性、准确度、精密度、耐用性、重复性和检测限等方面 ,对该方法进行了认证。组分迁移时间的 RSD<0 .2 %。 N-甲基吡咯烷在 0 .0 2～ 0 .4 0 mg/ ml的浓度范围内的线性相关系数为 1.0 0 0 0。对照品溶液重复进样的 RSD为0 .9% (n=10 )。对照品溶液和供试品溶液分析的日内精密度 (RSD)分别为 1.6 % (n=10 )和 2 .9% (n=6 )     

毛细管电泳法测定黄酮类化合物(英文)

黄酮类化合物由于其在生物学及生理学中的重要作用受到了广泛的关注。本文综述了毛细管电泳法测定黄酮类化合物的应用,包括手性分离以及毛细管电泳-质谱联用技术。此外,还讨论了提高毛细管电泳法灵敏度的技术,如样品堆积法、扫集法和等速电泳法等。     

硫酸化环糊精在毛细管电泳手性拆分中的应用

综述近年来硫酸化环糊精在毛细管电泳手性药物拆分方面中的应用。对随机取代的硫酸化环糊精、单一异构体的硫酸化环糊精及多元环糊精体系的结构特点，及其在手性药物对映体拆分中的影响因素、条件优化和应用实例进行了讨论。硫酸化环糊精以良好的水溶性和强劲的手性识别能力应用于毛细管电泳的手性拆分，可使对映体获得较好的分离效果。