Ordered mesoporous silica functionalized with beta-cyclodextrin derivative for stereoisomer separation of flavanones and flavanone glycosides by nano-liquid chromatography and capillary electrochromatography

In this paper a chiral stationary phase (CSP) was prepared by the immobilization of a beta-CD derivative (3,5-dimethylphenylcarbamoylated beta-CD) onto the surface of amino-functionalized spherical ordered mesoporous silica (denoted as SM) via a urea linkage using the Staudinger reaction. The CSP was packed into fused silica capillaries 100 mu m I.D. and evaluated by means of nano-liquid chromatography (nano-LC) and capillary electrochromatography (CEC) using model compounds for the enantio- and the diastereomeric separation. The compounds flavanone, 2'-hydroxyflavanone, 4'-hydroxyflavanone, 6hydroxyflavanone, 4'-methoxyflavanone, 7-methoxyfiavanone, hesperetin, hesperidin, naringenin, and naringin were studied using reversed and polar organic elution modes. Baseline stereoisomer resolution and good results in terms of peak efficiency and short analysis time of all studied flavonoids and flavanones glycosides were achieved in reversed phase mode, using as mobile phase a mixture of MeOH/H2O, 10 mM ammonium acetate pH 4.5 at different ratios. For the polar organic mode using 100% of MeOH as mobile phase, the CSP showed better performances and the baseline chiral separation of several studied compounds occurred in an analysis time of less than 10 min. Good results were also achieved by CEC employing two different mobile phases. The use of MeOH/H2O, 5 mM ammonium acetate buffer pH 6.0 (90/10, v/v) was very effective for the chiral resolution of flavanone and its methoxy and hydroxy derivatives. (C) 2017 Elsevier B.V. All rights reserved

The Role of Capillary Electrophoresis to Guarantee the Quality and Safety of Dietary Supplements

At present, dietary supplements are commercially available products, globally consumed as an addition to the usual diet. Considering that dietary supplements are a source of nutrients, they are widely utilized to improve human health and prevent various diseases; therefore they are expected to be safe. There is still no common definition regarding the role of supplements which cannot be considered functional foods nor drugs. Dietary ingredients in supplements are exempt from food additives or drugs regulations. For this reason, these supplements are marketed without any data on identity, including ingredient information, effectiveness, toxicology and safety. Therefore, efficacy and safety are necessary claims required to preserve consumer health. To face this imperative challenge, sensitive and selective analytical techniques capable of providing a full characterization of the supplements in terms of their components are needed. In the last decades, Capillary Electrophoresis (CE) has shown to be a powerful tool that offers solutions to almost any analytical issue arising in several application fields. Due to its simplicity of operation and versatility, it has become a complementary separation tool to other separation techniques such as gas and liquid chromatography in the analysis of dietary supplements. This chapter aims to give a comprehensive overview of the most important applications of CE for the analysis of dietary supplements in terms of their main key components.</jats:p

Analysis of natural antioxidants by capillary electromigration methods

In this work, an exhaustive survey of capillary electromigration methods used to analyze natural antioxidants is presented together with some discussion of the use of these substances use as functional foods. This review provides an updated and exhaustive overview of the separation and identification by capillary electrophoresis of natural compounds with antioxidant activity found in natural matrices and/or foods. The compounds concerned are catechins, isoflavones, anthocyanins, phenolic acids, vitamins, as well as other less common natural substances that have shown antioxidant activity.MH would like to thank MCYT for a FPI grant. Authors thank MCYT (project AGL2002-04621-C02-02) for financial support.Peer reviewe