Capillary electrophoresis with capacitively coupled contactless conductivity detection for the determination of urinary ethylmalonic acid for the diagnosis of ethylmalonic aciduria

Application of capillary electrophoresis with capacitively contactless conductivity detection for biomedical analysis

The coupling of capillary electrophoresis (CE) with capacitively coupled contactless conductivity detection (C4 D) has become convenient analytical method for determination of small molecules that do not possess chromogenic or fluorogenic group. The implementations of CE with C4 D in the determination of inorganic and organic ions and amino acids in biomedical field are demonstrated. Attention on background electrolyte composition, sample treatment procedures, and the utilize of multi-detection systems are described. A number of tables summarizing highly developed CE-C4 D methods and the figures of merit attained are involved. Lastly, concluding remarks and perspectives are argued.

Highly sensitive rapid determination of orotic acid in urine samples using a field-amplified sample stacking approach in capillary electrophoresis coupled with contactless conductivity detection

Orotic aciduria is a severe, hereditary, life-threatening condition, particularly in newborns. An increased orotic acid (OA) content in urine may be a strong indicator of this condition. In this study, we developed a rapid, simple, highly sensitive diagnostic method for use in monitoring the OA levels in urine samples, which were successfully determined using capillary electrophoresis combined with capacitively coupled contactless conductivity detection (CE-C4D). A straightforward analysis with an increased sensitivity towards OA and an analysis time of approximately 5 min were realized, and the limit of detection of the developed method was 0.014 mg/L in aqueous solution. The optimized composition of the separation electrolyte was 20 mM 2-(N-morpholino)ethanesulfonic acid/histidine with 0.1 mM cetyltrimethylammonium bromide at a pH of 6.5. The sensitivity of the developed method was significantly increased using a sample stacking approach with a 10% acetonitrile (v/v) plug solution. The method was validated, and satisfactory recoveries of 80.0-92.3% were obtained. The amounts of OA in five urine samples were successfully determined.

Separation and quantification of the urinary enantiomers of 2-hydroxyglutaric acid by capillary electrophoresis with capacitively coupled contactless conductivity detection: Application to the diagnosis of D- and L-2-hydroxyglutaric aciduria

2-hydroxyglutaric aciduria is an inherited neurometabolic disorder with two major types: D-2-hydroxyglutaric aciduria and L-2-hydroxyglutaric aciduria. An easy and fast capillary electrophoresis system combined with a capacitively coupled contactless conductivity detection method was developed for the enantioseparation and determination of D- and L-2-hydroxyglutaric acid in urine. D- and L-2-hydroxyglutaric acids were separated using vancomycin as the chiral selector. The optimal separation conditions for enantiomers were achieved by the use of a buffer containing 50 mM 4-(N-morpholino) butane sulfonic acid solution (pH 6.5), an electroosmotic flow modifier (0.001% [w/v] polybrene), and 30 mM vancomycin as chiral selector. The analysis time was 6 min under optimal conditions. The optimized and validated method was successfully implemented for quantifying D- and L-2-hydroxyglutaric aciduria in patients' urine, without any pretreatment step. The linearity of the method was determined to be in the range of 2-100 mg/L for D- and L-2-hydroxyglutaric acid in urine. The precision (relative standard deviation%) was obtained at about 7%. For D- and L-2-hydroxyglutaric acids, the limits of detection were 0.567 and 0.497 mg/L, respectively.

Applications of capillary electrophoresis in the fields of environmental, pharmaceutical, clinical and food analysis (2019-2021)

So far, the potential of capillary electrophoresis (CE) in the application fields has been increasingly excavated due to the advantages of simple operation, short analysis time, high-resolution, less sample consumption and low cost. This review examines the implementations and advancements of CE in different application fields (environmental, pharmaceutical, clinical and food analysis) covering the literature from 2019 to 2021. In addition, ultrasmall sample injection volume (nanoliter range) and short optical path lead to relatively low concentration sensitivity of the most frequently used UV-absorption spectrophotometric detection, so the pretreatment technology being developed has been gradually utilized to overcome this problem. Despite the review is focused on the development of CE in the fields of environmental, pharmaceutical, clinical and food analysis, the new sample pretreatment techniques of microextraction and enrichment which fit excellently to CE in recent three years are also described briefly. This article is protected by copyright. All rights reserved.

An online target and rapid screening method for α-glucosidase inhibitors based on capillary electrophoresis

Screening enzymatic active compounds is one of the important fields in drug research. α-Glucosidase can hydrolyze carbohydrates to monosaccharides after meals and lead to the rise of blood glucose levels in human body. Thus, the inhibition of α-glucosidase activity is an effective approach for the diabetes treatment. In this work, we developed a new method to simultaneously screen multiple bioactive compounds within a single CE running. The affect factors on the method performance, including injection, mixing, incubation, separation and detection, were carefully analyzed and discussed. Under the optimum, the mixture consisting of two internal standards (DMSO and 4-nitrophenol) and five compounds (lyoniresinol, hydroxytyrosol, rutin, kaempferol, and quercetin) was simultaneously screened, and kaempferol and quercetin showed stronger activity and this conclusion was also supported by offline assay. Furthermore, molecular docking was employed for investigating its interaction mechanism. Eventually, the established method has been applied to screen potential α-glucosidase inhibitors from an extract of Lycium barbarum and the peak area of rutin, taxifolin, quercetin, and chlorogenic acid in L. barbarum samples changed before and after the enzymatic reaction, confirming that these four compounds had potential inhibitory activities, which was consistent with the literature data. The present work provides a promising method for the target and rapid discovery of bioactive compounds from a plant extract or mixture.

Capacitively coupled contactless conductivity detection for analytical techniques - Developments from 2018 to 2020

The developments of analytical contactless conductivity measurements based on capacitive coupling over the two years from mid-2018 to mid-2020 are covered. This mostly concerns applications of the technique in zone electrophoresis employing conventional capillaries and to a lesser extent lab-on-chip devices. However, its use for the detection in several other flow-based analytical methods has also been reported. Detection of bubbles and measurements of flow rates in two-phase flows are also recurring themes. A few new applications in stagnant aqueous samples, e.g. endpoint detection in titrations and measurement on paper-based devices, have been reported. Some variations of the design of the measuring cells and their read-out electronics have also been described.

Application of Capillary Electrophoresis with Capacitively Coupled Contactless Conductivity Detection (CE-C4D): 2017-2020

Capacitively coupled contactless conductivity detection (C⁴D) has emerged as influential to detect analytes that do not have chromogenic or fluorogenic functional group. Since our last review several new capillary electrophoresis (CE) methods coupled with (CE-C⁴D) have been communicated. The aim of this review is to give an update of the almost all the new applications of CE-C⁴D in the field of pharmaceutical, food and biomedical analysis covering the period from 2017 to April 2020. The utilization of CE with C⁴D in the areas of pharmaceutical, food and biomedical analysis is presented. Finally, concluding remarks and outlooks are discussed.