Principles Of Capillary Electrophoresis Research Articles

Sensitivity enhancement in capillary electrophoresis and their applications for analyses of pharmaceutical and related biochemical substances.

This review aims to illustrate sensitivity enhancement methods in capillary electrophoresis (CE) and their applications for pharmaceutical and related biochemical substance analyses. The first two parts of the article describe the introduction and principle of CE. The main part focuses on strategies for sensitivity improvement in CE including detector and capillary technologies and preconcentration techniques. Applications of these techniques for pharmaceutical and biomedical substance analyses are surveyed during the years 2018-2021.

Évaluation de la concordance des valeurs d'hémoglobine glyquée entre les automates de biochimie D-10® (Biorad) et Minicap Flex piercing® (Sebia)

Glycated hemoglobin (HbAlc) is a key marker in the management of diabetic patients, particularly for the monitoring of glycemic control. Today, various automated glycated hemoglobin assay systems are available on the market. Thus, in order to meet one of the requirements of the ISO 15189 standard, a study was carried out in order to evaluate the agreement between the results obtained by two biochemical machines, in particular the D-10® (Biorad) system based on an ion exchange HPLC method and the Minicap Flex Piercing® (Sebia) that uses the principle of capillary electrophoresis. In total, thirty samples covering the measurement interval defined by the suppliers were tested and for each sample the assays were performed in parallel on the two automata. We found a good correlation between the two systems with a coefficient R = 0.995 (p <0.0001). The difference diagram according to Bland and Altman shows a distribution of differences for both normal HbAlc values and high values (> 86 mmol/mol or 10%). Ninety-five percent of the differences are between - 0.93 and + 11.33 mmol/mol (or - 0.08% and + 1.01%). This large range of differences does not allow to affirm a transferability between the two systems and require the follow-up of patients with the same technique.

An Overview of CE in Clinical Analysis.

The development and general applications of capillary electrophoresis (CE) in the field of clinical chemistry are discussed. It is shown how the early development of electrophoresis was closely linked to clinical testing. The rise of gel electrophoresis in clinical chemistry is described, as well as the eventual developments that lead to the creation and the use of modern CE. The general principles of CE are reviewed and the potential advantages of this method in clinical testing are examined. Finally, an overview is presented of several areas in which CE has been developed and is currently being explored for use with clinical samples.

Capillary Electrophoresis in Determination of Low Molecular Mass Organic Acids

 Abstract—This paper presents overviews the capabilities of capillary electrophoretic techniques to determine low molecular mass organic acids in a variety of aqueous, gas and solid samples. It mainly focuses on short - chain carboxylic acids containing one or more carboxylic groups and possibly some other functional groups (hydroxyl, keto-, amino- etc.). Finally the procedures applied to the determine the acids in different matrices are shortly characterized. The principles of capillary electrophoresis its advantages over gas and liquid chromatographic separation and detection modes are briefly discussed. Finally, the brief overview of the technique is followed by characterization of CE based procedures for the analysis of a variety of samples such as food, environmental, biological etc. for the content of organic acids, mainly those with carboxylic groups.

キャピラリー電気泳動装置の原理と分析事例

キャピラリー電気泳動装置の原理と分析事例

Recent advances of capillary electrophoresis in pharmaceutical analysis

This review covers recent advances of capillary electrophoresis (CE) in pharmaceutical analysis. The principle, instrumentation, and conventional modes of CE are briefly discussed. Advances in the different CE techniques (non-aqueous CE, microemulsion electrokinetic chromatography, capillary isotachophoresis, capillary electrochromatography, and immunoaffinity CE), detection techniques (mass spectrometry, light-emitting diode, fluorescence, chemiluminescence, and contactless conductivity), on-line sample pretreatment (flow injection) and chiral separation are described. Applications of CE to assay of active pharmaceutical ingredients (APIs), drug impurity testing, chiral drug separation, and determination of APIs in biological fluids published from 2008 to 2009 are tabulated.

Electrochemical detection of acetylcholine and choline: application to the quantitative nonradiochemical evaluation of choline transport

The development of analytical methods for determining the cholinergic biomarkers acetylcholine (ACh) and choline (Ch) is important for assessing their role in neurological and cognitive functions. In this review, electrochemical (EC) strategies to detect ACh and Ch are summarized and compared to other analysis methods. Recent research focusing on the development of a versatile nonradiochemical in vitro assay to evaluate Ch transport is also described. The assay coupled to analysis by capillary electrophoresis (CE) with indirect EC detection at an enzyme-modified microelectrode affords exceptional selectivity and sensitivity. Femtomole or lower mass detection limits for ACh (1 fmol) and Ch (100 amol) have been readily achieved, opening up a new range of possible experiments for investigating transport or turnover of Ch and ACh in neurobiological systems. The value of this method is illustrated through the evaluation of the pharmacological efficacy and mode of inhibition of a new class of quaternary ammonium alkyl-substituted catechol-based inhibitors of high-affinity choline transport (CHT). This microanalytical approach is particularly useful when knowledge of endogenous concentrations of Ch or ACh is desired or when the amount of available compounds or the sample size is limited. A brief description of the principles of CE is also provided.

Estimation of pKa values using microchip capillary electrophoresis and indirect fluorescence detection

Microchip capillary electrophoresis (CE), coupled with indirect fluorescence detection was investigated for estimating the pK(a) values of non-fluorescent compounds. The CE method is based on the differences in electrophoretic mobility of the analyte as a function of the pH of the running buffer. Nine compounds were tested, including several of pharmaceutical importance, with pK(a) values from 10.3 to 4.6. All buffers contained 5-TAMRA as the fluorescent probe for indirect detection. Calculated pK(a) values agreed well with literature values obtained by traditional methods, differing not more than 0.2 from the literature value. The current work on single lane chips demonstrates the principle of microchip CE with indirect detection as a viable method for estimating pK(a) values. However, increased throughput will be required using a multilane chip to enable the approach to be used practically.

Development of a chip‐based capillary gel electrophoresis method for quantification of a half‐antibody in immunoglobulin G4samples

A method based on microfluidic technology was developed to support quantitative analysis of recombinant monoclonal immunoglobulin G4 (IgG4) antibody samples. The assay was performed on an Agilent 2100 Bioanalyzer in combination with the Protein 200 Plus LabChip Kit and the Protein 200 Plus assay software. Capillary electrophoresis principles have been transferred to a chip format that integrates all separation, staining, virtual destaining, and detection steps. The method is referred to in this paper as chip-based capillary gel electrophoresis (GelChip-CE method). The GelChip-CE method under nonreducing conditions proved to be a quantitative test for half-antibody determination in IgG4 samples. Similar to the traditional nonreducing sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) method, the GelChip-CE method includes a denaturing step prior to separation. We showed that denaturing the sample by heating resulted in an artificial increase in the amount of half-antibody detected, which could be prevented by addition of N-ethylmaleimide to the sample buffer. The GelChip-CE method allowed for analysis of IgG4 samples with more accuracy, higher precision, and a faster turnaround time than SDS-PAGE and reversed-phase high-performance liquid chromatography (RP-HPLC).

Progress of capillary electrophoresis in therapeutic drug monitoring and clinical and forensic toxicology.

During the past decade, capillary electrophoresis (CE) emerged as a promising, effective, and economical approach for the analysis of licit and illicit drugs and their metabolites in biologic samples. This review provides an overview of the principles of CE, the features of CE instrumentation, and the key aspects of CE-based drug assays that were developed for therapeutic drug monitoring (TDM), clinical and forensic toxicology, and assessment of drug metabolism and pharmacokinetics. CE performed in fused-silica capillaries has sufficiently matured and can thus be applied routinely, whereas chip-based instrumentation comprising fully integrated assays is still in development. Despite the attractive advantages of electrokinetic capillary technology, relatively few CE-based assays for TDM and for drug screening of clinical and forensic interest have been adopted in the routine arena. The lack of complete systems designed for unattended operation, the reluctance of bioanalysts to replace a satisfactory existing method, and tight budgets are believed to have hindered the widespread replacement of older (mainly chromatographic) technology. Another limitation of CE is that this technique is somewhat less sensitive than other analytic techniques used for drug analysis in biologic fluids. New instrumental developments featuring user-friendly software and the introduction of assay kits, however, should increase the number of validated CE drug tests becoming used on a routine basis.

Pherogram normalization in capillary electrophoresis and micellar electrokinetic chromatography analyses in cases of sample matrix-induced migration time shifts

When analyzing bio-matrix samples using capillary electrophoresis (CE) or micellar electrokinetic chromatography (MEKC), unwanted shifts in the time axis are often observed, both between samples and standards and between samples, thus hampering identification. These shifts are caused by either or both of two sample matrix-induced effects: variations in stacking conditions (effective field strength or migration length) and variations in electroosmotic flow. Based on elementary CE principles and provided that any two peaks in the pherograms can be linked, these variations can be separately accounted and quantitatively corrected for, so that perfectly overlapping pherograms of standards and samples can be obtained after normalization. The method was validated using samples of a DNA ladder, separated in a sieving polymer. In addition, a number of data files from CE and MEKC analyses (steroids, opioids, β-blockers, amines, and inorganic anions) previously published by other authors were successfully normalized. A freeware computer programme, CEqualizer, for normalizing ASCII files of detector signals using the method described, is available to the CE community from http://www.ceyork.f2s.com.

New approaches for fabrication of microfluidic capillary electrophoresis devices with on-chip conductivity detection.

In practice, microfluidic systems are based on the principles of capillary electrophoresis (CE), for a large part due to the simplicity of electroosmotic pumping. In this contribution, a universal conductivity detector is presented that allows detection of charged species down to the microM level. Additionally, powderblasting is presented as a novel technique for direct etching of microfluidic networks. This method allows creation of features down to 50 microm with a total processing time (design to device) of less than one day. The performance of powderblasted devices with integrated conductivity detection is illustrated by the separation of lithium, sodium, and potassium ions and that of fumaric, malic, and citric acid.

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.

Combined thermal field-flow fractionation–capillary electrophoresis

The possibility of using the transverse thermophoresis of analytes in the capillary used in capillary electrophoresis (CE) to control the separation process was considered, thus decreasing the spreading of the thermal peak and providing new separation parameters in CE. The Joule heating in non-aqueous buffers in the CE capillary can provide transverse temperature gradients comparable to temperature gradients in conventional equipment for thermal field-flow fractionation (ThFFF). It is proposed to use the non-uniform velocity profile of analytes caused by transverse temperature gradient and the temperature dependence of the buffer viscosity for the FFF-like separation of analytes in addition to CE separation. The expressions for the peak parameters are derived, taking into account the non-uniform transverse analyte distribution due to the thermophoresis, and the possibilities based on FFF–CE principles are discussed. As possible objects of this hyphenated technique, macromolecules and particles are considered.

Fundamentals of capillary electrophoresis theory.

This section will describe the fundamental theory, equations, and definitions necessary to comprehend the concepts involved in capillary electrophoresis (CE). This is not an exhaustive treatment, but is considered sufficient to comprehend and appreciate the principles of CE. More detailed theoretical background can be obtained from a number of reference books (, , , , , ). Developments in the field of CE are reviewed in detail annually in the journal Analytical Chemistry. For example, the 801 papers published in 1992–1993 were recently reviewed ().

Anion screening for drugs and intermediates by capillary ion electrophoresis

A method is described to screen bulk pharmaceuticals and their synthetic intermediates for common anions. Capillary electrophoresis (CE) is a rapid separation technique which operates on the basis of the differential migration of charged and uncharged species in an electric field. Capillary ion electrophoresis utilizes the principles of CE in combination with an osmotic flow modifier and indirect UV detection for the rapid determination and quantification of ions. A Waters Quanta 4000 capillary electrophoresis system, equipped with a 60 cm × 75 μm I.D. fused-silica capillary in conjunction with a patented chromate buffer and osmotic flow modifier is used. The detection limit of the assay is 0.5 μ/ml for most anions. Parameters have been optimized so that all analytes migrate within 5.0 min. A number of optimization experiments for parameters such as loading time, voltage, linearity, precision and detection limit of the system are demonstrated. The effects of the presence of organic solvents in the sample diluents on the migration times of anions are examined. Applications of the technique to pravastatin sodium, taxol and iopiperidol are illustrated. Comparison to ion chromatography, advantages and disadvantages, is discussed.