Determination of Ascorbic Acid in Commercial Juices, on a Modified Carbon Paste Electrode, by Using a Taguchi Experimental Design

Abstract

In this paper, a simple and rapid analytical method development for ascorbic acid determination by using differential pulse voltammetry method on copper(II)-phthalocyanine carbon paste electrode is shown. For this, several parameters, such as copper(II)-phthalocyanine (gram)/carbon (gram)/Nujol (millilitre) ratio, supporting electrolyte, pH and some others have been studied. In order to know the copper(II)-phthalocyanine influence on voltammetry peak height, a comparison between the analytical behaviour of a chemically modified carbon paste electrode and a conventional carbon paste electrode was carried out. The experimental conditions have been optimised by means of the experimental design using the Taguchi methodology. The catalytic oxidation peak current showed a linear depending on the ascorbic acid concentration in the range between 0.88 and 10.03 mg L−1, with the detection limit of 0.55 mg L−1. The proposed procedure was successfully applied to the determination of ascorbic acid in fruit juices without previous preparation and was compared with HPLC method applied at the same samples previously filtered.