Capillary zone electrophoresis of lipoarabinomannan by multi-layered concentration

The present paper describes a capillary zone electrophoresis method which relies on a multi-layered water-alkali solvent stacking with on-line ionization to enhance detection of mannose, arabinose, and their oligosaccharides, which are used as the migration profile standards but are also the distinctive structural components of lipoarabinomannan. Lipoarabinomannan is detected in patients having tuberculosis. The CE method with ionization of the whole saccharides without degradation in alkaline solution inside the capillary is based structural deprotonation of the molecules under ultrahigh pH conditions. The validation of the CE parameters revealed that the 15-fold electrolyte - water -injection plug allowed detection of one third lower concentrations than detected without on-line concentration. For the first time, the better detectability was seen especially for highly polymerized, but otherwise poorly ionized, arabino-octaose. The applicability of the method for detecting whole large biological saccharide complexes was confirmed by the glycolipid lipoarabinomannan. For the first time also, the migration of the indestructible lipoarabinomannan was detected together with oligosaccharides used representing the capping units, namely mannose, mannobiose and mannotriose. The myo-inositol-phosphate-lipid unit was seen to migrate separately from the arabinomannan, since it was hydrolyzed from one lipoarabinomannan product under alkaline conditions in CE. This article is protected by copyright. All rights reserved.

Partial least squares model and design of experiments toward the analysis of the metabolome of Jatropha gossypifolia leaves: Extraction and chromatographic fingerprint optimization

A major challenge in metabolomic studies is how to extract and analyze an entire metabolome. So far, no single method was able to clearly complete this task in an efficient and reproducible way. In this work we proposed a sequential strategy for the extraction and chromatographic separation of metabolites from leaves Jatropha gossypifolia using a design of experiments and partial least square model. The effect of 14 different solvents on extraction process was evaluated and an optimized separation condition on liquid chromatography was estimated considering mobile phase composition and analysis time. The initial conditions of extraction using methanol and separation in 30 min between 5 and 100% water/methanol (1:1 v/v) with 0.1% of acetic acid, 20 μL sample volume, 3.0 mL min(-1) flow rate and 25°C column temperature led to 107 chromatographic peaks. After the optimization strategy using i-propanol/chloroform (1:1 v/v) for extraction, linear gradient elution of 60 min between 5 and 100% water/(acetonitrile/methanol 68:32 v/v with 0.1% of acetic acid), 30 μL sample volume, 2.0 mL min(-1) flow rate, and 30°C column temperature, we detected 140 chromatographic peaks, 30.84% more peaks compared to initial method. This is a reliable strategy using a limited number of experiments for metabolomics protocols.

Capillary Electrophoresis in Food and Foodomics

Quality and safety assessment as well as the evaluation of other nutritional and functional properties of foods imply the use of robust, efficient, sensitive, and cost-effective analytical methodologies. Among analytical technologies used in the fields of food analysis and foodomics, capillary electrophoresis (CE) has generated great interest for the analyses of a large number of compounds due to its high separation efficiency, extremely small sample and reagent requirements, and rapid analysis. The introductory section of this chapter provides an overview of the recent applications of capillary electrophoresis (CE) in food analysis and foodomics. Relevant reviews and research articles on these topics are tabulated including papers published in the period 2011-2014. In addition, to illustrate the great capabilities of CE in foodomics the chapter describes the main experimental points to be taken into consideration for a metabolomic study of the antiproliferative effect of carnosic acid (a natural diterpene found in rosemary) against HT-29 human colon cancer cells.

Simple and robust monitoring of ethanol fermentations by capillary electrophoresis

Free-solution capillary electrophoresis (CE), or capillary zone electrophoresis, with direct UV detection was used for the first time for the determination of mono- and disaccharides, sugar alcohols, and ethanol in fermentation broths. Sample preparation proved to be minimal: no derivatization or specific sample purification was needed. The CE conditions can be adapted to the type of fermentation by simply altering the background electrolyte (BGE). KOH (130 mM) or NaOH (130 mM) as the BGE led to the fastest analysis time when monitoring simple fermentations. A mixture of 65 mM NaOH and 65 mM LiOH led to a 19% improvement in resolution for a complex mixture of carbohydrates. Quantification of a simple carbohydrate fermentation by CE showed values in close agreement with that of high-performance anion exchange chromatography and high-performance liquid chromatography (HPLC) on a cation exchange resin. For complex fermentations, quantification of carbohydrates by HPLC and CE led to similar results, whereas CE requires an injection volume of only 10-20 nL. Analysis of an ethanol fermentation of hydrolyzed plant fiber demonstrated the robustness of the separation and detection of carbohydrates, as well as ethanol. Ethanol determination is achieved by coupling the CE method to pressure mobilization, using the same instrument and the same sample.

Advance of CE and CEC in phytochemical analysis (2012–2013)

This article presents an overview of the advance of CE and CEC in phytochemical analysis, based on the literature not mentioned in our previous review papers [Chen, X. J., Zhao, J., Wang, Y. T., Huang, L. Q., Li, S. P., Electrophoresis 2012, 33, 168–179], mainly covering the years 2012–2013. In this article, attention is paid to online preconcentration, rapid separation, and sensitive detection. Selected examples illustrate the applicability of CE and CEC in biomedical, pharmaceutical, environmental, and food analysis. Finally, some general conclusions and future perspectives are given.