Miniaturized matrix solid-phase dispersion and solid-phase clear-up combined with capillary electrophoresis for efficient determination of trace bioactive components in complicated sample matrix: Take Wubi Shanyao Pill as an example

Accurate quantitative analysis of trace analytes in a complicated matrix is a challenge in modern analytical chemistry. An appropriate analytical method is considered to be one of the most common gaps during the whole process. In this study, a green and efficient strategy based on miniaturized matrix solid-phase dispersion and solid-phase extraction combined with capillary electrophoresis was first proposed for extracting, purifying and determining target analytes from complicated matrix, using Wubi Shanyao Pill as an example. In detail, 60 mg of samples were dispersed on MCM-48 to obtain high yields of analytes, then the extract was purified with a solid-phase extraction cartridge. Finally, four analytes in the purified sample solution were determined by capillary electrophoresis. The parameters affecting the extraction efficiency of matrix solid-phase dispersion, purification efficiency of solid-phase extraction and separation effect of capillary electrophoresis were investigated. Under the optimized conditions, all analytes demonstrated satisfactory linearity (R²>0.9983). What's more, the superior green potential of the developed method for the determination of complex samples was confirmed by the Analytical GREEnness Metric Approach. The established method was successfully applied in the accurate determination of target analytes in Wubi Shanyao Pill and thus provided reliable, sensitive, and efficient strategy support for its quality control.     

Potencies of ligand-exchange capillary electrophoresis in the determination of biologically active compounds

The analytical potencies of ligand-exchange capillary electrophoresis (LECE) in regard to the determination of bioactive substances are discussed. As it is shown, complexation with copper(II) in the electrophoretic determination with UV detection makes possible the determination of amino acids, amines, and sugars, which do not absorb in the UV region, with the limits of detection 5–10 mg/L, and reduce the detection limits of the absorbing analytes, such as tryptophane, tyrosine, and histamine by 2–3 times. Prospects for using online preconcentration for the reduction of c _min are shown on an example of aliphatic amino acids, i.e., thirtyfold preconcentration is attained. LECE is shown to be applicable to the simultaneous determination of glucose, Na(⁺), and K(⁺) in human blood serum. Also versions of ligand-exchange capillary electrophoresis with direct UV detection and capillary zone electrophoresis with indirect one are compared in terms of efficiency, time of analysis, and limit of detection. The potencies of the LECE method are compared with those of ligand-exchange chromatography.     

Determination of preservatives in soft drinks by capillary electrophoresis with ionic liquids as the electrolyte additives

A capillary electrophoresis method for separating preservatives with various ionic liquids as the electrolyte additives has been developed. The performances for separation of the preservatives using five ionic liquids with different anions and different substituted group numbers on imidazole ring were studied. After investigating the influence of the key parameters on the separation (the concentration of ionic liquids, pH, and the concentration of borax), it has been found that the separation efficiency could be improved obviously using the ionic liquids as the electrolyte additives and tested preservatives were baseline separated. The proposed capillary electrophoresis method exhibited favorable quantitative analysis property of the preservatives with good linearity (r² = 0.998), repeatability (relative standard deviations ≤ 3.3%) and high recovery (79.4–117.5%). Furthermore, this feasible and efficient capillary electrophoresis method was applied in detecting the preservatives in soft drinks, introducing a new way for assaying the preservatives in food products.     

Simultaneous determination of caffeine,paracetamol, and ibuprofen in pharmaceutical formulations by high‐performance liquid chromatography with UV detection and by capillary electrophoresis with conductivity detection

Paracetamol, caffeine and ibuprofen are found in over‐the‐counter pharmaceutical formulations. In this work, we propose two new methods for simultaneous determination of paracetamol, caffeine and ibuprofen in pharmaceutical formulations. One method is based on high‐performance liquid chromatography with diode‐array detection and the other on capillary electrophoresis with capacitively coupled contactless conductivity detection. The separation by high‐performance liquid chromatography with diode‐array detection was achieved on a C₁₈ column (250×4.6 mm², 5 μm) with a gradient mobile phase comprising 20–100% acetonitrile in 40 mmol L^?1 phosphate buffer pH 7.0. The separation by capillary electrophoresis with capacitively coupled contactless conductivity detection was achieved on a fused‐silica capillary (40 cm length, 50 μm i.d.) using 10 mmol L^?1 3,4‐dimethoxycinnamate and 10 mmol L^?1 β‐alanine with pH adjustment to 10.4 with lithium hydroxide as background electrolyte. The determination of all three pharmaceuticals was carried out in 9.6 min by liquid chromatography and in 2.2 min by capillary electrophoresis. Detection limits for caffeine, paracetamol and ibuprofen were 4.4, 0.7, and 3.4 μmol L^?1 by liquid chromatography and 39, 32, and 49 μmol L^?1 by capillary electrophoresis, respectively. Recovery values for spiked samples were between 92–107% for both proposed methods.     

Light-emitting-diode-induced fluorescence detector for capillary electrophoresis using optical fiber with spherical end

A simple fluorescence detector for capillary electrophoresis (CE) using a blue light-emitting-diode (LED) as excitation source is constructed and evaluated. An optical fiber was used to collect the fluorescence, and a flat end of the fiber was modified to spherical end, resulting in 50% increase of efficiency over the flat end. A simple device for optical alignment of the fibers and capillary column was designed. The concentration and mass detection limits for fluorescein were 1.8×10⁻⁷ mol l⁻¹ and 4.3 femol, respectively.     

毛细管电泳在农药残留检测上的应用

对近20年来毛细管电泳分析方法在农药残留分析中的应用进行了论述.按照农药的用途分类,分别评述了应用毛细管电泳分析检测杀虫剂和杀菌剂以及除草剂残留的研究进展,并对毛细管电泳在农药残留分析中的应用进行了展望.     

Electrophoretic and gas-chromatographic analysis of an Afobazol pharmaceutical preparation

Procedures for determining 5-ethoxy-2-[2-(morpholino)ethylthio]benzimidazole dihydrochloride, an active component of the Afobazol medicinal preparation, and its potential impurities, 5-ethoxybenzimidazol-2-thione and N-(2-chloroethyl)morpholine hydrochloride by capillary zone electrophoresis in the range 2.0 × 10^?5 to 2.0 × 10^?3 M and ligand-exchange capillary electrophoresis in the range 1.0 × 10^?5 to 5.0 × 10^?3 M are developed. The optimum conditions for the separation and determination of these analytes using a quartz capillary tube are found. The reliability of the results obtained by capillary electrophoresis was confirmed by gas chromatography with a mass-selective detector.     

金纳米修饰毛细管电泳分离氨基苯甲酸

报道了一种金纳米修饰毛细管电泳分离、测定氨基苯甲酸的新方法。采用制备的金纳米进行了石英毛细管修饰。探讨了修饰金纳米浓度、修饰时间以及缓冲溶液加入一定浓度的金纳米对三种氨基苯甲酸分离和测定的影响,优化了分离电压、酸度以及缓冲溶液浓度等实验条件。结果表明金纳米的存在,显著的改进了氨基苯甲酸分离的选择性,增强了分离效率。在优化的实验条件下,进行了邻、间、对三种氨基苯甲酸的分离和测定。线性浓度范围为0.5–40 µg·mL,相关系数0.9978-0.9992。检测限(S/N = 3) 为0.1-0.5µg·mL。     

Rapid separation of basic drugs by nonaqueous capillary electrophoresis

Summary Nonaqueous capillary electrophoresis (NACE) has been used to achieve rapid separations of basic drugs. A high electric field was obtained by using short capillaries. Baseline separations of basic drugs, including amphetamines, tropane alkaloids and local anesthetics, were achieved in 1 min by selection of the appropriate organic solvent and electrolyte composition. Thus, high-throughput analyses can be performed. Peak efficiency up to 9154 theoretical plates s⁻¹ was achieved in a separation performed at 923V cm⁻¹. No discernible loss in resolution was observed when a conventional capillary (64.5cm) was replaced by a short (32.5 cm) capillary.     

3-Mercaptopropyltrimethoxysilane coated capillary micro-extraction coupled to capillary electrophoresis for the determination of methylmercury, phenylmercury and mercury in biological sample

A simple method for the separation of methylmercury, phenylmercury and mercury(II) in biological sample was developed. The novel method was targeted on extraction of mercury species using a 3-mercaptopropyltrimethoxysilane coated capillary, and determined by capillary electrophoresis with ultraviolet absorption detection. The effects of pH, sample volume and flow rate, eluent volume and flow rate on the efficiency of micro-extraction were investigated. Under the optimized conditions, the detection limits (S/N?=?3) of MeHg, PhHg and Hg²⁺ were 0.012, 0.007 and 0.003 µg mL^?1, respectively. The precisions (RSDs) of the peak area and the migration time for five replicate injections of the three species after capillary micro-extraction were 6.4%, 8.3%, 5.3% and 1.2%, 1.3%, 1.8%, respectively. The method was successfully applied to the determination of mercury species in biological sample.     

Electrophoretic analysis of proteins and enantiomers using capillaries modified by a successive multiple ionic-polymer layer (SMIL) coating technique

The applicability of three-layer coatings consisting of three different polymers (A⁺-B⁻-C⁺ coating) prepared by a successive multiple ionic-polymer layer (SMIL) coating technique to the immobilization of polypeptides and/or proteins onto the inner surface of the capillaries was investigated to provide a high-performance separation medium for proteins and enantiomers in capillary electrophoresis (CE). To obtain a stable protein-coated capillary, high molecular mass poly(ethyleneimine) (PEI) was employed as the first layer in the A⁺-B⁻-C⁺ coating, and then a cationic protein was immobilized as the third layer. Comparisons of analytical performances between the A⁺-B⁻-C⁺ coating and the conventional SMIL-coated (A⁺-B⁻-A⁺ coating) capillary were conducted. The CE separation of cationic proteins was successfully achieved with the prepared capillaries. In addition, the polypeptide- and protein-coated capillaries were applied to the chiral separation of a binaphthyl compound. It should be noted that the chiral separation efficiency was strongly dependent on the second anionic polymer layer of the coating. Effects of the interaction between oppositely charged ionic polymer layers on the separation efficiency are discussed.     

免疫亲和毛细管电泳的研究进展

免疫亲和毛细管电泳方法结合了免疫分析的高特异性和毛细管电泳分离的高效、快速、样品用量少等优点,是复杂样品中特定组分分析的重要方法之一。激光诱导荧光检测器的使用以及毛细管电泳分离前免疫预富集过程的引入,可以进一步提高分析测定的灵敏度,使其能够用于痕量物质的高灵敏测定。本文结合作者所在课题组的工作,对免疫亲和毛细管电泳的两种主要模式,即均相的毛细管电泳免疫分析(CEIA)和非均相的免疫亲和毛细管电泳(IACE)的研究进展进行了综述。     

Determination of Pyromellitic Acid in Aqueous Matrices by CE

An analytical method for the capillary electrophoresis determination of pyromellitic acid in aqueous media used as “food simulants” has been developed and is described in this paper. The proposed method determined the pyromellitic acid at ppb levels and is based on a capillary zone electrophoresis separation using coated fused-silica capillary column with a carbonate running buffer and a UV-Vis detector. The method herein developed has been applied to the determination of pyromelitic acid residues leached from plastic bottles. The amount of pyromellitic acid determined in different batch of polyethyleneterephthalate bottles is 2.18%, while the limit of detection is 2.30 ng mL^?1 with a relative standard deviation of 4.40%.     

On‐site sampling of inorganic contamination on the metal surface and analysis with capillary electrophoresis

Pipes are the primary structural elements used for transporting fluid in various industries. The most common damage mechanism is corrosion, which occurs in pipes surface of turbine. The corrosive compounds for pipes are inorganic ion (Na⁺, Cl^?, NH₄⁺, NO₃^?, etc.) and grinding oil. For rapid and quantitative detection of inorganic ions on site, more reliable and reproducible analytical methods are demanded. A highly efficient solid–liquid sampling collection system is introduced in this work. Papering on the sample surface, inorganic cations and anions were simultaneously collected and analyzed by capillary electrophoresis with indirect ultraviolet detection. As a result, five cations (Na⁺, K⁺, NH₄⁺, Ca²⁺, Mg²⁺) and three anions (Cl^?, NO₃^?, SO₄^2?) were completely separated. The efficiency of the sampling and ability of capillary electrophoresis analysis were presented by the determination of trace‐level (mg/m²) contaminants. The recoveries of cations and anions on the paper from metal surface were between 86.6 and 107.2%, and the relative standard deviations were less than 12.85%.     

Comparison of various capillary electrophoretic approaches for the study of drug–protein interaction with emphasis on minimal consumption of protein sample and possibility of automation†

The binding ability of a drug to plasma proteins influences the pharmacokinetics of a drug. As a result, it is a very important issue in new drug development. In this study, affinity capillary electrophoresis, capillary electrophoresis with frontal analysis, and Hummel Dreyer methods with internal and external calibration were used to study the affinity between bovine serum albumin and salicylic acid. The binding constant was measured by all these approaches including the equilibrium dialysis, which is considered to be a reference method. The comparison of results and other considerations showed the best electrophoretic approach to be capillary electrophoresis‐frontal analysis, which is characterized by the high sample throughput with the possibility of automation, very small quantities of biomacromolecules, simplicity, and a short analysis time. The mechanism of complex formation was then examined by capillary electrophoresis with frontal analysis. The binding parameters were determined and the corresponding thermodynamic parameters such as Gibbs free energy ΔG⁰, enthalpy ΔH⁰, and entropy changes ΔS⁰ at various temperatures were calculated. The results showed that the binding of bovine serum albumin and salicylic acid was spontaneous, and that hydrogen bonding and van der Waals forces played a major role in the formation of the complex.     

Separation of arsenic anions by capillary zone electrophoresis with UV detection

Summary Capillary zone electrophoresis (CZE) in capillary silica columns has been used for the separation of arsenite (AsO ₂ ^– ), arsenate (AsO ₄ ^3– ), monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA). The separation of these ionic species has been achieved using a capillary silica column (72 cm×50 m i.d.) with an acidic phosphate buffer and with an on-column UV detection (190 nm). Optimization of experimental parameters (pH, temperature, voltage) were studied. The selectivity of the separation can be improved by working in the pH-range of 4.5–6.5. For analytical inorganic separations of UV-absorbing anions, capillary zone electrophoresis has advantages because of the relatively simple equipment, the short analysis time (15 min), the high efficiency and the low mass detection limit (40 pg for arsenate).     

毛细管电泳在火炸药研究中的应用

近年来,毛细管电泳以其高效、快速、微量的特点,在火炸药分析领域被广泛应用并迅速发展。本文从毛细管区带电泳、胶束电动毛细管色谱、毛细管电色谱、芯片毛细管电泳、微乳毛细管电动色谱这五种毛细管电泳的模式出发,结合本实验室的最新研究进展,综述毛细管电泳在火炸药研究中的应用。     

On-line sample preconcentration in capillary electrophoresis. Fundamentals and applications

On-line preconcentration is one of the aspects of analytical method development using capillary electrophoretic techniques. The choice of the sample matrix alone can significantly alter both method sensitivity and separation efficiency. The recent trend to detect samples in narrower separation vessels also necessitates the need to improve detection sensitivity. The desire to detect very low levels of analytes using limited amounts of sample from biological specimens and the high separation efficiency obtainable using very large injections compared to classical small size injections also adds to this list. Indeed, one of the rich areas of research in the capillary electrophoresis field is on on-line sample preconcentration. More than 400 published research articles gathered from the http://www.webofscience.com from the year 2000 described a form of on-line preconcentration in capillary electrophoresis. This review provides a comprehensive table listing the applications of on-line preconcentration in capillary electrophoresis.     

毛细管电泳在生物大分子分析中的应用研究进展

近年来,毛细管电泳技术以其高效、微量、分离模式多样等优势,在生物大分子分析领域得到了日益广泛的应用.综述了毛细管电泳技术在多糖、蛋白质、核酸和脂质中的应用,并对其相关的样品制备、毛细管内壁吸附、仪器的研制等方面存在的问题进行分析和展望,以期为毛细管电泳技术在生物大分子领域的推广应用提供借鉴.     

Simple in‐house flow‐injection capillary electrophoresis with capacitively coupled contactless conductivity method for the determination of colistin

An in‐house flow‐injection capillary electrophoresis with capacitively coupled contactless conductivity detection method was developed for the direct measurement of colistin in pharmaceutical samples. The flow injection and capillary electrophoresis systems are connected by an acrylic interface. Capillary electrophoresis separation is achieved within 2 min using a background electrolyte solution of 5 mM 2‐morpholinoethanesulfonic acid and 5 mM histidine (pH 6). The flow‐injection section allows for convenient filling of the capillary and sample introduction without the use of a pressure/vacuum manifold. Capacitively coupled contactless conductivity detection is employed since colistin has no chromophore but is cationic at pH 6. Calibration curve is linear from 20 to 150 mg/L, with a correlation coefficient (r²) of 0.997. The limit of quantitation is 20 mg/L. The developed method provides precision, simplicity, and short analysis time.