Elektrochemische Oxydation von Flavonoiden an einer glasartigen Kohlenstoffelektrode

Rapid Voltammetric Screening Method for the Assessment of Bioflavonoid Content Using the Disposable Bare Pencil Graphite Electrode

Hesperidin (HESP) is a plant bioflavonoid found in various nutritional and medicinal products. Many of its multiple health benefits rely on the compound’s antioxidant ability, which is due to the presence of oxidizable hydroxyl groups in its structure. Therefore, the present study aimed to investigate the electrochemical behavior of HESP at a cheap, disposable pencil graphite electrode (PGE) in order to develop rapid and simple voltammetric methods for its quantification. Cyclic voltammetric investigations emphasized a complex electrochemical behavior of HESP. The influence of the electrode material, solution stability, supporting electrolyte pH, and nature were examined. HESP main irreversible, diffusion-controlled oxidation signal obtained at H type PGE in Britton Robinson buffer pH 1.81 was exploited for the development of a differential pulse voltammetry (DPV) quantitative analysis method. The quasi-reversible, adsorption-controlled reduction peak was used for HESP quantification by differential pulse adsorptive stripping voltammetry (DPAdSV). The linear ranges of DPV and DPAdSV were 1.00 × 10−7–1.20 × 10−5 and 5.00 × 10−8–1.00 × 10−6 mol/L with detection limits of 8.58 × 10−8 and 1.90 × 10−8 mol/L HESP, respectively. The DPV method was applied for the assessment of dietary supplements bioflavonoid content, expressed as mg HESP.

Analysis of Food by High Performance Liquid Chromatography Coupled with Coulometric Detection and Related Techniques: A Review

The development of single coulometric cells in combination with high performance liquid chromatography to dual cells and to the coulometric electrode array detector is described. An overview is given about the application of these methods in food chemistry. Easily oxidizable compounds, such as phenolic substances, pesticides, or vitamins, can be determined, as well as substances with high oxidation potentials or electroinactive compounds. Substances exhibiting poor electrochemical activity can be transformed to electroactive compounds by precolumn derivatization, postcolumn photochemical reactions, postcolumn enzyme reactors, or by using the oxidative/reductive mode for coulometric electrode array detection. Furthermore, it is shown that the interesting combination of high performance liquid chromatography with electrochemistry and mass spectrometry has opened further possibilities with respect to interpretation of redox reactions, drug metabolism studies, metabolomics, and electrochemical derivatization.

Determination of matairesinol in flax seed by HPLC with coulometric electrode array detection

A HPLC method coupled with coulometric electrode array detection for the determination of matairesinol in flax seed is described. The defatted sample was spiked with bisphenol A (internal standard), refluxed for 75 min in a mixture of ethanol-bidistilled water-12 M hydrochloric acid (2:2:1, v/v/v) to extract matairesinol conjugates and to hydrolyze them simultaneously. The extract was diluted with mobile phase [250 ml acetonitrile-750 ml buffer (730 ml bidistilled water, 20 ml glacial acetic acid adjusted to pH 3 with 5 M sodium hydroxide)] and injected into the HPLC system. Matairesinol was separated from other compounds on a reversed-phase column (Lichrospher 60 RP-Select B, 250 x 4 mm, 5 micro m) and detected in a coulometric electrode array detector using a flow-rate of 0.8 ml/min. The potentials of the eight electrodes were set on +150, +200, +250, +300, +350, +400, +550 and +600 mV against modified palladium electrodes. The content of matairesinol determined in seven samples varies between 7 and 28.5 micro g/g. The limit of quantitation is 5 micro g/g.