Application Of Micellar Electrokinetic Chromatography Research Articles

Annual review of capillary electrophoresis technology in 2020

该文为2020年毛细管电泳(capillary electrophoresis, CE)技术年度回顾。归纳总结了以“capillary electrophoresis-mass spectrometry”或“capillary isoelectric focusing”或“micellar electrokinetic chromatography”或“capillary electrophoresis”为关键词在ISI Web of Science数据库中进行主题检索得到的2020年CE技术相关研究论文222篇,以及中文期刊《分析化学》和《色谱》中CE技术相关的研究论文37篇。对2020年影响因子(IF)≥5.0的Analytical Chemistry, Food Chemistry, Analytica Chimica Acta和Talanta等13本期刊的38篇文章报道的科研工作作了逐一介绍;对IF<5.0的期刊中CE技术报道较为集中的Journal of Chromatography A和Electrophoresis两本分析化学类期刊发表40篇文章中的代表性内容作了综合介绍;对重要的中文期刊《分析化学》出版的“核酸适配体专刊”和《色谱》出版的2期CE技术专刊所收录的37篇文章中的工作作了总体介绍。总体来说,2020年CE技术发展趋势仍以毛细管电泳-质谱(CE-MS)的新方法和新应用最为突出,主要集中在CE-MS与电化学检测、固相萃取以及多种毛细管电泳模式的联用方面,CE-MS接口相关的报道较前几年有所减少;常规CE技术则以胶束电动毛细管色谱(MEKC)在复杂样本分析、浓缩富集应用为主,尤其在食品和药品等复杂基质样本分析方面的报道较为集中;此外,我国CE相关领域专家学者的科研成果涵盖了CE在生命科学、临床医学、医药研发、环境科学、天然产物、食品分析等领域的应用,代表了国内CE科研应用水平和现状。

Application of micellar electrokinetic chromatography for detection of silver nanoparticles released from wound dressing.

The recent emergence of nanotechnology has provided a new therapeutic modality in case of silver nanoparticles. Dressings containing silver form the basis for the treatment of burns and wounds, either acute or chronic ones. The aim of the study was to examine silver release from the different wound dressings: commercially available (Atrauman Ag, Aquacel Ag) and experimental (FKDP-AgNPs) using MEKC. In order to characterize prepared keratin based wound dressing before and after its modification with AgNPs, a compositional analysis was conducted using energy dispersive X-ray spectroscopy. Nanosilver toxicity was evaluated with the 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4 sulfophenyl)-2H-tetrazolium test. Silver release from wound dressings was assessed using MEKC. The best separation was observed for MEKC in 20 mM borate buffer at pH 9 with 20 mM SDS addition. In vitro studies showed silver at higher concentration than 10ppm exerted a toxic effect on fibroblasts isolated from diabetic mice versus. NIH/3T3 and BJ cell lines (p<0.05). We observed silver was released more gradually from experimental FKDP-AgNPs wound dressing, in compare to commercially available wound dressings. The fast and low-cost method utilizing MEKC can be used in clinical practice to detect silver release from the wound dressings.

Free and bound phenolic compounds in barley ( Hordeum vulgare L.) flours : Evaluation of the extraction capability of different solvent mixtures and pressurized liquid methods by micellar electrokinetic chromatography and spectrophotometry

Phenolic compounds exist in free and bound forms in cereals. The efficiency, reliability and suitability of recovering free phenolic compounds from barley by conventional, solid–liquid and pressurized solvent extractions, using different mixtures and methods, were tested. The extraction recovery of bound phenolics was evaluated using alkaline and acid hydrolyses. This study illustrates a rapid application of micellar electrokinetic chromatography for the analysis of free and bound phenolic compounds in barley samples. After developing a capillary electrophoresis optimization plan, barley phenols were analyzed within 5.5 min, using a buffer containing 20 mM sodium tetraborate, 10 mM sodium dodecyl sulfate and 5 mM KH 2PO 4 (pH 9), a 40 cm × 50 μm capillary, 30 kV and 30 °C. The selectivity of the extraction methods in recovering phenolic classes was evaluated by capillary electrophoresis and compared with spectrophotometric measurements. Electropherograms of free phenolic extracts showed flavan-3-ol compounds, proanthocyanidins and hydrolysable tannins. Aqueous acetone and aqueous ethanol solvents extracted the highest amount of catechins and hydrolysable tannins, respectively. The extraction yield of bound phenolic compounds (especially hydroxycinnamic acids) increased when the digestion time for alkaline hydrolysis was prolonged.

Application of micellar electrokinetic chromatography to the determination of sultamicillin in oral pharmaceutical preparations.

A micellar electrokinetic capillary electrophoretic method for determination of sultamicillin in Unasyn oral preparations--tablets and suspension--was evaluated. Phosphate-borate buffer at pH 7.0 containing 1.0% sodium dodecylsulfate was used as a mobile phase. The elaborated method ensures separation of sultamicillin from p-toluenesulfonic acid and the impurities, ampicillin, sulbactam and penicillamine. The method was validated for specificity, reproducibility, precision, accuracy and assay linearity (in a concentration range of sultamicillin of 0.05-1.5 mg/ml). Statistical analysis by Student's t-test showed no significant differences between the results obtained by micellar electrokinetic chromatography and HPLC, t(calculated) 0.519 for suspension assays and 0.284 for tablets assays were smaller then t(tabulated).

Application of micellar electrokinetic chromatography to the quality control of a pharmaceutical preparation containing three bronchodilators.

Theophylline(1,3-dimethylxanthine), dyphylline [7-(2,3-dihydroxypropyl)theophylline] and proxyphylline [7-(beta-hydroxypropyl)theophylline] are three bronchodilators administered jointly in a single pharmaceutical preparation used against asthma. A micellar electrokinetic chromatography (MEKC) method for their resolution using a background electrolyte consisting of 20 mM tetraborate at pH 8.5 and 100 mM sodium dodecyl sulfate is proposed. The method was used to determine the three active principles in a pharmaceutical preparation. The small amount of sample required and the expeditiousness of the procedure allow content uniformity to be determined in individual tablets. The values of the validation parameters for the method (viz. selectivity, linearity, accuracy, precision, limit of detection, limit of quantitation and robustness) are reported. A complete factor design (2(3)x2) including pH, the surfactant concentration and the ionic strength of the background electrolyte as factors was used to estimate robustness. Based on the results, the method is robust enough for quantitation purposes.

Applicability of micellar electrokinetic chromatography to the analysis of estrogens in water.

Estrone, beta-estradiol and ethynylestradiol spiked in water were extracted using solid-phase extraction (SPE) and then directly determined by micellar electrokinetic chromatography (MEKC) with online concentration (sweeping). A 350 mL original sample volume (10 nM each) was concentrated to 1 mL using SPE, and ca. 240 nL of this solution was injected onto an MEKC capillary column. After sweeping, the estrogen related compounds were detected using a commercial absorbance detection system with an LOD of 0.16-0.30 nM in the original sample.

Applicability of Micellar Electrokinetic Chromatography with a Double-Chain Surfactant Having Two Sulfonate Groups to the Determination of Pollutant Phenols in Water

Applicability of Micellar Electrokinetic Chromatography with a Double-Chain Surfactant Having Two Sulfonate Groups to the Determination of Pollutant Phenols in Water

Application of micellar electrokinetic chromatography for the separation of retinoids

The applicability of micellar electrokinetic chromatography (MEKC) using sodium dodecylsulphate (SDS) as pseudo-stationary phase for the separation of five retinoids (retinol, retinal, retinyl acetate, retinyl palmitate, retinoic acid), was investigated. The effects of the acetonitrile content, the SDS concentration, the pH and the addition of Brij 35 to the background electrolyte on the migration behaviour of the retinoids were determined. It was found that the effective mobilities of retinol, retinal and retinyl acetate could be easily regulated through the ACN content and the SDS concentration of the BGE. The electrophoretic behaviour of the very hydrophobic retinyl palmitate was abnormal. Under various conditions this compound showed up as a late, very sharp peak. A strong indication was found that the retinyl palmitate forms a stable, charged complex with SDS during sample preparation. The mobility of the retinyl palmitate peak could be regulated, independently from the other peaks, through the Brij concentration of the BGE. Using a running buffer consisting of Tris–buffer (pH 8), 20 mmol l −1 SDS, 1 mmol l −1 Brij 35 and 35% (v/v) acetonitrile, a complete separation of the five retinoids could be realised in less than 20 min.

Applicability of micellar electrokinetic chromatography to kinetic studies of photocatalytic oxidation of dibenzo- p-dioxin

Micellar electrokinetic chromatography (MEKC) using sodium dodecyl sulfate was tested for its ability to analyze mixtures containing three dioxin derivatives. Dioxin-containing samples, subjected to photocatalytic oxidation using TiO 2 and/or SnO 2 as the semiconductor catalyst were analyzed by MEKC to obtain the rate constant for each dioxin when it was degraded individually or in the presence of the other two dioxins. A significant degree of analyze competition was observed and the mixed catalyst offered important synergism.

Application of micellar electrokinetic chromatography for analyzing antiviral drugs in pharmaceutical semisolid formulations

The application of micellar electrokinetic chromatography (MEKC) to the determination of the antiviral drugs brivudin (BV) and aciclovir (AC) in pharmaceutical semisolid formulations was studied. A method was developed for separating AC and BV both from hydrophilic and from lipophilic semisolid formulations and for the rapid determination of BV and AC using MEKC. The detection limit, the effective mobility and the relative standard deviation of the migration times and of the peak areas were determined.

Quantitative structure-activity relationships studies with micellar electrokinetic chromatography influence of surfactant type and mixed micelles on estimation of hydrophobicity and bioavailability

Applications of micellar electrokinetic chromatography (MEKC) in quantitative structure-activity relationships (QSAR) were studied. First, quantitative structure-retention relationships (QSRR), which describe the correlation between logarithm of capacity factor (log k′) in MEKC and logarithm of distribution coefficient between 1-octanol and water (log P ow), were investigated for 60 aromatic compounds and 9 corticosteroids using three different anionic surfactants [e.g., sodium dodecyl sulfate (SDS), sodium cholate (SC), and lithium perfluorooctane sulfonate (LiPFOS)], one cationic surfactant (C 14TAB), and mixed anionic micellar systems. Linear solvation energy relationships (LSER) and solvatochromic parameters were used to shed light on the different log k′ vs. log P ow relationships for the various surfactants. It was concluded that hydrogen bonding interactions have a great influence on retention behavior in MEKC and its relationship with hydrophobicity. Interestingly, bile salt surfactants (e.g., SC) and mixed bile salt micellar systems provide better correlations for log k′ vs. log P ow than SDS and/or SDS with buffer additives (e.g., ß-cyclodextrin, urea, and acetonitrile). Using SC micelles, only one line was adequate to describe the relationship between retention in MEKC and hydrophobicity for a group of 60 aromatic compounds. The existence of higher correlation for the SC system was attributed to a similar hydrogen bonding pattern between SC micelles and 1-octanol. In the SDS system, however, three lines were recognized for the congeneric subgroups of compounds. This is due to the hydrogen bond donor (HBD) characteristics of SDS micelles that selectively differentiate between the solutes with different hydrogen bond acceptor (HBA) strength, thus demonstrating that retention is not solely based on hydrophobicity. A similar result was observed for a C 14TAB-MEKC system, however, the HBA characteristics of C 14TAB selectively differentiates between the solutes with different HBD strength. In addition, quantitative retention-activity relationships in MEKC were also investigated for 9 corticosteroids. Two types of biological activities [small intestinal absorption in the rat (log A/NA) and protein binding to human serum albumin (log B/F)] were examined in this work. High correlations were observed between bioactivity and log k′ in MEKC using bile salt surfactants and mixed bile salt systems.

MEKC analysis of FITC and DTAF amino acid derivatives with LIF detection

The application of micellar electrokinetic chromatography to the analysis of complex mixtures of FITC and DTAF amino acid derivatives was studied. Resolution optimization was attempted for a mixture of 21 amino acids. In the case of FITC, by increasing the analysis temperature to 35 °C, a total of 17 FITC amino acids could be separated. On the other hand, by using a combination of mixed micelles (SDS/Brij-35) and the addition of organic modifiers, a total of 19 DTAF derivatized amino acids could be separated.

Application of micellar electrokinetic chromatography and indirect UV detection for the analysis of fatty acids

A micellar electrokinetic chromatographic system using indirect UV detection was developed for the analysis of saturated fatty acids. Sodium dodecyl benzenesulfonate (SDBS) was used as micellar surfactant as well as chromophore for the indirect detection. The effects of the addition of acetonitrile and Brij on the migration and solubility of the fatty acids was investigated. With a mixture of 10 m M SDBS + 50% acetonitrile + 30 m M Brij, a complete separation of the C 8-C 20 fatty acids was obtained. The applicability of the developed system for the analysis of fatty acids in butter is demonstrated.

Biological Sciences and Analytical Chemistry. Application of micellar electrokinetic chromatography for monitoring the kinetic resolution of sulfoxides by dimethyl sulfoxide reductase.

Recently, micellar electrokinetic chromatography (MEKC) has been successfully applied to the separation of electrically neutral compounds. In this study, we applied this method in order to determine simultaneously organic sulfoxide and sulfide; benzyl methyl sulfoxide (BMSO) and benzyl methyl sulfide (BMS), respectively. Dimethyl sulfoxide (DMSO) reductase from Rhodobacter sphaeroides f. sp. denitrificans deoxygenates (S)-BMSO preferably. The MEKC method gave reliable estimates of BMSO concentration without any pretreatment, therefore, the (R)-isomer could be recovered with high enantiomeric excess by stopping the reaction at the conversion rate of 50%. Using this detection method, (R)-BMSO was recovered with good chemical and optical yields. The simple and rapid measurement by MEKC was proved to be suitable for the kinetic resolution of racemic sulfoxide by the enzymatic reaction.

Application of Micellar Electrokinetic Chromatography as a Novel Assay Method for Dimethyl Sulfoxide Reductase

A direct and simple assay method for dimethyl sulfoxide reductase (DMSO reductase) by determining dimethyl sulfoxide (substrate) and dimethyl sulfide (product) in a reaction mixture of the enzyme was developed. Micellar electrokinetic chromatography (MEKC), a kind of capillary electrophoresis, was quite effective for a quantitative determination below the nanogram level without any pretreatment of the reaction mixture.

Capillary liquid chromatography-mass spectrometry and micellar electrokinetic chromatography as complementary techniques in environmental analysis

Applications of capillary electrophoresis (CE) and capillary liquid chromatography (LC) to environmental analysis have been limited. In this work we present applications of micellar electrokinetic chromatography (MEKC) to the analysis of environmental matrices for synthetic dyes. Separations obtained by capillary LC are compared with those obtained under MEKC for seven selected dyes. Both techniques are capable of resolving the subject compounds at high efficiency. Recovery data for spiked water and soil matrices were obtained for four dyes using solid-phase extraction cartridges and disks with determination by MEKC-UV detection. Both pH adjustment via acid and ion-pairing via a cationic surfactant were investigated for isolating dyes. Capillary LC detection was by continuous-flow liquid secondary ion mass spectrometry (CF-LSI-MS) whereas MEKC used UV detection (214 nm). Application of peak-profiling at high mass resolution is illustrated with the capillary LC-MS technique. Interfacing capillary LC under CF-LSI-MS using the coaxial arrangement is easier than interfacing CE with this arrangement. MEKC provides a powerful screening and determinative technique, while capillary LC-MS provides a confirmatory tool.

Applications of MEKC in the Determination of Benzidines Following Extraction from Water, Soil, Sediment, and Chromatographic Adsorbents

Micellar electrokinetic chromatography (MEKC) with ultra-violet detection is used to determine benzidine (4,4′-di-aminobiphenyl) and three substituted analogues (3,3′-dimethoxybenzidine, 3,3′-dimethylbenzidine, and 3,3′-dichlorobenzidine) in water, soil, and sediment. Recovery of benzidines from chromatographic adsorbents is also determined by MEKC. The use of short capillaries makes possible the determination of benzidines in soil extracts in about 2 minutes after solid-phase extraction cleanup with C18 cartridges. Although benzidines are determined down to 10 ng/g in water, problems are encountered in the extraction of benzidines from soil and sediment matrices and from chromatographic adsorbents. Several solvent systems are investigated with moderate success for extraction of benzidines at contaminant levels in the µg/g range for soil. MEKC of additional aromatic amines is carried out, allowing assessment of the specificity of the determination.

Application of micellar electrokinetic chromatography to the quality control of pharmaceutical formulations: the analysis of xanthine derivatives.

Micellar electrokinetic chromatography (MEKC) has been applied to the analysis of three different drugs. Although belonging to different therapeutic classes, all these drugs contain xanthine derivatives as active substances. Pentoxifylline was separated from eight related xanthines. Quantitative MEKC was applied to determine impurities (caffeine and xanthine) in the purified drug at the 0.05-0.1% level and also for the determination of the active substance in Agapurin tablets. Ethofylline and theophylline were separated from ephedrine and mebrophenhydramine and determined in Xantedrylettae tablets while caffeine was separated from mephenhydramine and determined in Kinedryl tablets. In all cases, simple borate buffers with sodium dodecyl sulfate as the surfactant were satisfactory and little separation optimization was required. The relative standard deviation (RSD) of the migration times was better than 1% while the RSD of the observed areas was better than 2%. This demonstrates that MEKC is a valuable alternative for the traditional high-performance liquid chromatography analysis of drugs and drug formulations.

Application of micellar electrokinetic chromatography to pharmaceutical analysis

Electrokinetic chromatography is a new type of analytical separation method which belongs to the group of high performance capillary electrophoretic techniques but whose separation principle is based on that of chromatography. The solute distributes itself between a carrier and the surrounding medium. The carrier, which corresponds to the stationary phase in conventional chromatography, can be transported by electrophoresis with a different velocity from the surrounding medium. The separation is achieved by the differential solute distribution and the differential migration of the carrier. The charged molecules or charged molecular aggregates are employed as the carrier. Various kinds of carriers are available for electrokinetic chromatography along with different partition mechanisms. Among them, micellar electrokinetic chromatography, which employs an ionic micelle as a carrier, has become the most popular method because of its unique and attractive characteristics as well as the separating capability of electrically neutral or nonionic solutes in comparison with capillary zone electrophoresis. The present paper describes the principle, separation characteristics and its application to the analysis of pharmaceuticals.