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Rapid determination of ascorbic acid, dehydroascorbic acid, and total vitamin C by electrochemiluminescence with a thin-layer electrochemical cell

Author:
Takahashi, Fumiki, Jin, Jiye
Source:
Analytical and bioanalytical chemistry 2009 v.393 no.6-7 pp. 1669-1675
ISSN:
1618-2642
Subject:
ascorbic acid, beverages, dehydroascorbic acid, electrochemiluminescence, electrochemistry, oxidation, pH, phosphates
Abstract:
This paper reports on a rapid and sensitive method for the simultaneous determination of ascorbic acid (H₂A), dehydroascorbic acid (DHA), and total vitamin C by electrochemiluminescence (ECL) using a thin-layer electrochemical cell. Significant ECL signals can be generated by the anodic oxidation of Ru(bpy)₃ ²⁺ in the presence of H₂A or DHA in pH 8.8 phosphate buffer solution. Because of the extremely small dead volume of the thin-layer cell (approximately 1.5 μL), almost all amount of H₂A is assumed to be completely oxidized to DHA with a short pre-electrolysis step. As a result, it is possible to determine the reductive vitamin C (H₂A) by square wave voltammetry before the pre-electrolysis step, while total vitamin C (sum of H₂A and DHA) is able to be determined at a subsequent ECL step. The method was employed for the determination of vitamin C in commercial beverages with the analytical results in good agreement with the certified values. [graphic removed]
Agid:
2173600