Kinetic spectrophotometric method for the determination of oxalic acid by its catalytic effect on the oxidation of safranine by dichromate

A new catalytic kinetic spectrophotometric method for the determination of oxalic acid has been described based on its catalytic effect on the redox r eaction between safranine and dichromate in dilute sulfuric acid media. The reaction is monitored photometrically by measuring the decrease in absorba nce of safranine at the maximum wavelength of 530 nm. Under the optimum con ditions, a calibration graph from 0.10 to 10.00 mug ml(-1) of oxalic acid w ith a detection limit of 0.08 mug ml(-1) was obtained. The relative standar d deviation (R.S.D.) for ten replicate measurements of 1.0 and 5.0 mug ml(- 1) oxalic acid was 2.7 and 2.5%, respectively. The purposed method is simpl e. sensitive, selective and inexpensive. The applicability of the proposed method was determined by the determination of oxalic acid in spinach and wa stewater samples with satisfactory results. (C) 2001 Elsevier Science B.V. All rights reserved.