APPLICATION AND ADVANTAGES OF THE ENZYMATIC METHOD FOR THE ASSAY OF ASCORBIC AND DEHYDROASCORBIC ACIDS AND REDUCTONES Determination in Fresh and Canned Spinach

Abstract

A new enzymatic method based on the reaction ascorbic acid +½O2→ dehydroascorbic acid + H2O permits assaying for ascorbic and dehydroascorbic acids in vegetable extracts. The method is carried out using a Clark's electrode which determines the oxygen uptake during the above reaction. The method applied to both fresh and canned spinach is specific and reproducible. Some interfering substances may reduce the specificity and precision of the method, but the addition of chelating agents or acetaldehyde eliminates these interferences. On adding boric acid, only the interfering reductic acid is assayed. The ascorbic and dehydroascorbic acid values for fresh spinach range between 528–919 mg/100g for ascorbic acid and from 21–81 mg/100g for dehydroascorbic acid. For canned spinach the ascorbic acid values ranged from 119–202 mg/100g and the dehydroascorbic acid values from 25–110 mg/100g. The method is easy and rapid and can be utilized advantageously for routine analyses.

Electroanalysis of ascorbic acid (vitamin C) using nano-ZnO/poly(luminol) hybrid film modified electrode

“…Traditional procedures for AsA determination are generally based on enzymatic methods [3], on titration with oxidizing agents, like iodine or 2,6-dichlorophenolindophenol [4] and HPLC analysis with fluorimetric [4] or UV-vis detection [5,6]. Recently there is a considerable interest to develop chemical sensors for electrochemical detection of AsA.…”

Quantification ofL-ascorbic acid and total ascorbic acid in fruits and spinach by capillary zone electrophoresis

“…The quantity of L-AA was not significantly different when 5% metaphosphoric acid solution was used for extraction, followed by incubation in a dark place at 237C for 4 h [25]. The low pH value (pH 5 2) of metaphosphoric acid solution is responsible for the denaturation of ascorbic acid oxidase [24,26] as well as for the stabilization of L-AA in acidic pHs [27]. The presence of EDTA was also indicated to be beneficial for the stability of L-AA by chelating some free ions such as Fe +2 , Sn +2 and Cu + [28,29].…”

“…L-AA is liable to degradation and the maintenance of L-AA stability during sample preparation and quantitative analysis has been endeavored by the addition of metaphosphoric acid [24,25]. The quantity of L-AA was not significantly different when 5% metaphosphoric acid solution was used for extraction, followed by incubation in a dark place at 237C for 4 h [25].…”

Analytical Application of Pyramidal, Rodlike, and Spherical Gold Nanostructures: Simultaneous Detection of Ascorbic Acid and Uric Acid

“…Abnormal levels of UA are effective indicator of several diseases, such as gout, immunodefficiency, and Lesch -Nyan syndrome [8]. Several methods, like colorimetric, enzymatic [9] and electrochemical techniques based on modified electrodes have been employed for the determination of AA and UA. The electrochemical strategies have been received much interest, because of their striking characteristics, such as low cost, good selectivity, quick response time, and so on.…”