Chemometrics-guided development of a cyclodextrin-modified micellar electrokinetic chromatography method with head-column field amplified sample stacking for the analysis of 5-lipoxygenase metabolites

Abromeit, Hans; Schaible, Anja; Werz, Oliver; Scriba, Gerhard K. E.

doi:10.1016/j.chroma.2012.08.001

Cited by 14 publications

(17 citation statements)

References 34 publications

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“…Under the optimization of the separation condition, the effect of sample matrix, sample injection time, polarity switching time, and reversed polarity were selected for further optimization of stacking condition. Using pure methanol as sample matrix increased peak area and peak height . However, the results demonstrated that a stable system without frequent current breakdown could be obtained employing 50% methanol in the sample matrix instead of 70 or 100% methanol.…”

Section: Resultsmentioning

confidence: 91%

“…Due to the lipophilicity of the compounds and their comparable charge densities, an MEKC system was initially used . In terms of migration time and resolution of analytes, the effect of the pH and concentrations of buffer, SDS, β‐CD and organic modifier, separation voltage, and temperature on the detection of DPPH and six antioxidants were investigated.…”

Section: Resultsmentioning

confidence: 99%

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The in‐capillary DPPH‐capillary electrophoresis‐the diode array detector combined with reversed‐electrode polarity stacking mode for screening and quantifying major antioxidants in Cuscuta chinensis Lam

Liu

Tian

et al. 2016

Electrophoresis

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An in-capillary 2, 2-diphenyl-1-picrylhydrazyl (DPPH)-CE-the DAD (in-capillary DPPH-CE-DAD) combined with reversed-electrode polarity stacking mode has been developed to screen and quantify the active antioxidant components of Cuscuta chinensis Lam. The operation parameters were optimized with regard to the pH and concentration of buffer solution, SDS, β-CDs, organic modifier, as well as separation voltage and temperature. Six antioxidants including chlorogenic acid, p-coumaric acid, rutin, hyperin, isoquercitrin, and astragalin were screened and the total antioxidant activity of the complex matrix was successfully evaluated based on the decreased peak area of DPPH by the established DPPH-CE-DAD method. Sensitivity was enhanced under reversed-electrode polarity stacking mode and 10- to 31-fold of magnitude improvement in detection sensitivity for each analyte was attained. The results demonstrated that the newly established in-capillary DPPH-CE-DAD method combined with reversed-electrode polarity stacking mode could integrate sample concentration, the oxidizing reaction, separation, and detection into one capillary to fully automate the system. It was considered a suitable technique for the separation, screening, and determination of trace antioxidants in natural products.

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Section: Resultsmentioning

confidence: 91%

Section: Resultsmentioning

confidence: 99%

The in‐capillary DPPH‐capillary electrophoresis‐the diode array detector combined with reversed‐electrode polarity stacking mode for screening and quantifying major antioxidants in Cuscuta chinensis Lam

Liu

Tian

et al. 2016

Electrophoresis

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“…Supernatants of the incubation mixtures or cell lysates were analyzed. For example, 5-lipoxygenase could be monitored in polymorphonuclear leukocytes by MEKC [44] and MEEKC [45]. Using a set of 5-carboxyfluorescein-labeled peptides, multiple protein kinases could be monitored in cell lysates [46].…”

Section: Pre-capillary Enzyme Assaysmentioning

confidence: 99%

Advances in Capillary Electrophoresis-Based Enzyme Assays

Scriba

Belal

2015

Chromatographia

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IntroductionEnzymes catalyze metabolic reactions in cells regulating homeostasis, growth and reproduction of living organisms. Enzymes are also often involved in human disease. The analysis of the human genome has revealed that within the so-called druggable genome a significant portion (in some analyses more than half) of the potential drug targets are enzymes [1][2][3]. Consequently, enzymes are important targets in the development of new drugs. Moreover, enzymes play a role in the clinical diagnosis of diseases. Therefore, effective methods for characterization of enzymes as well as for the determination of their activity are important, for example, for the understanding of enzyme-mediated metabolic reactions or the identification of substrates and inhibitors for the treatment of human diseases.Capillary electrophoresis (CE) has been applied to enzyme analysis for more than 20 years since the first report by Banke et al. on an assay of alkaline protease [4]. Since then, all aspects of enzyme-related analysis have been studied by CE methods including the evaluation of enzymatic activity, enzyme kinetics, identification and characterization of enzyme inhibitors and activators as well as metabolic pathways as, for example, summarized in [5][6][7][8][9][10][11][12].Generally, CE-based enzyme assays can be divided in three groups, pre-capillary (offline) assays, in-capillary (online) assays and post-capillary assays. In the pre-capillary assays, all required components including enzyme, substrate, co-factors, etc., are mixed in a vial and incubated for an intended period of time. Subsequently, the reaction is quenched and an aliquot is subjected to CE analysis for the determination of substrate(s) and/or co-substrate(s) and/ or product(s). Multiple sampling or repeated sampling in combination with sequential runs for the determination of Abstract Capillary electrophoresis (CE) has become a flexible and accurate, high-efficiency analytical separation technique in many areas requiring only minute amounts of sample and chemicals. Thus, CE has also been recognized as a suitable technique to study enzymatic reactions including the determination of Michaelis-Menten kinetic data or the identification and characterization of inhibitors. The most often applied CE-based enzyme assay modes can be divided into two categories: (1) pre-capillary assays where incubations are performed offline followed by CE analysis of substrate(s) and/or product(s) and (2) in-capillary assays in which the enzymatic reaction and analyte separation are performed in the same capillary. In case of the in-capillary assays, the enzyme may be immobilized or in solution. The latter is also referred to as electrophoretically mediated microanalysis (EMMA), while in the case of immobilized enzyme the term immobilized enzyme reactor (IMER) is used. The present review summarizes the literature on CEbased enzyme assays published between January 2010 and April 2015. Immobilized enzyme reactors as well as microfluidic devices applied to the study of enzymatic a...

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“…Among these approaches, cCD consists of a two‐level fFD, i.e. a star design and a center point, and requires 2 f +2 f +1 experimental runs to examine f factors . The most influential factors are chosen by fFD and cCD, and the response data are then evaluated to predict the optimized condition.…”

Section: Introductionmentioning

confidence: 99%

Application of a multivariate approach for analyte focusing by micelle collapse‐micellar electrokinetic chromatography for analyzing sunscreen agents in cosmetics

Lin

Jiang

et al. 2015

Electrophoresis

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The operating parameters that affect the performance of the online preconcentration technique "analyte focusing by micelle collapse-MEKC (AFMC-MEKC)" were examined using a multivariate approach involving experimental design to determine the sunscreen agents in cosmetics. Compared to the single-variable approach, the advantage of the multivariate approach was that many factors could be investigated simultaneously to obtain the best separation condition. A fractional factorial design was used to identify the fewest significant factors in the central composite design (cCD). The cCD was adopted for evaluating the location of the minimum or maximum response in this study. The influences of the experimental variables on the response were investigated by applying a chromatographic exponential function. The optimized condition and the relationship between the experimental variables were acquired using the JMP software. The ANOVA analysis indicated that the Tris pH value, SDS concentration, and ethanol percentage influenced the separation quality and significantly contributed to the model. The optimized condition of the running buffer was 10 mM Tris buffer (pH 9.5) containing 60 mM SDS, 7 mM γ-CD, and 20% v/v ethanol. The sample was prepared in 100 mM Tris buffer (pH 9.0) containing 7.5 mM SDS and 20% v/v ethanol. The SDS concentration in the sample matrix was slightly greater than the CMC value that makes the micelle be easily collapsed and the analytes be accumulated in the capillary. In addition, sunscreen agents in cosmetics after 1000-fold dilution were successfully determined by AFMC-MEKC.

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Chemometrics-guided development of a cyclodextrin-modified micellar electrokinetic chromatography method with head-column field amplified sample stacking for the analysis of 5-lipoxygenase metabolites

Cited by 14 publications

References 34 publications

The in‐capillary DPPH‐capillary electrophoresis‐the diode array detector combined with reversed‐electrode polarity stacking mode for screening and quantifying major antioxidants in Cuscuta chinensis Lam

The in‐capillary DPPH‐capillary electrophoresis‐the diode array detector combined with reversed‐electrode polarity stacking mode for screening and quantifying major antioxidants in Cuscuta chinensis Lam

Advances in Capillary Electrophoresis-Based Enzyme Assays

Application of a multivariate approach for analyte focusing by micelle collapse‐micellar electrokinetic chromatography for analyzing sunscreen agents in cosmetics

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