Catalytic-kinetic determination of trace amount of oxalate in food and water samples by utilizing oxalate-crystal violetpotassiumdichromate system

This paper describes a new simple, sensitive and selective catalytic-kinetic-spectrophotometricmethod for the determination of trace amounts of oxalate. The method is based on the catalytic effect ofoxalate on the oxidation of crystal violet by dichromate in acidic media. The reaction was followed bymeasuring the decrease in absorbance of crystal violet at 630 nm (Amm of crystal violet in acidic solution).The dependence of sensitivity on the reaction variables was studied and discussed. Under the optimumconditions a fixed time procedure was used to obtain a linear calibration curve in the ranges of 0.20-5.5 ofoxalate. The calculated detection limit was 0.050 Jig mr 1• The standard deviations for ten replicatedeterminations of 0.40, 1.0, 1.8 and 2.5.Jig mr 1 of oxalate were 1.45%, 1.38%, 0.95% and 0.51%,respectively. The effect of the presence of various species, commonly associated with real samples was alsoinvestigated. The proposed method has been successfully appliedfor the determination ofoxalate in spinachand spiked water samples