Flow-injection catalytic spectrophotometric determination of oxalic acid using the redox reaction between Victoria blue B and dichromate

Abstract

A flow-injection catalytic method is developed for the determination of oxalic acid based on its catalytic effect on the redox reaction between Victoria blue B and potassium dichromate in dilute sulfuric acid medium. The reaction is monitored spectrophotometrically by measuring the decrease in the absorbance of Victoria blue B at the maximum absorption wavelength of 618 nm. A calibration graph from 1.0 to 80.0 μg ml −1 of oxalic acid and a detection limit of 0.8 μg ml −1 was obtained. The sampling rate was about 22 samples per hour. The proposed method is simple and inexpensive. The applicability of the method was demonstrated by the determination of oxalic acid in vegetable food, such as spinach and mushroom.