[Catalytic fluorimetric determination of trace oxalate]

A new catalytic fluorimetric method for the determination of trace oxalate has been developed. The method is based on the catalytic effect of oxalate on the oxidation of potassium dichromate with rhodamine B in sulfuric acid medium. The catalytic reaction takes place at 50 degrees C for 10 min in a water bath and is a pseudo-zero-order reaction. The regression equation of calibration graph is delta F = 8.42c (mg.L-1) + 3.81 (r = 0.9983), and measuring range is 0.4-12.0 mg.L-1, and the detection limit is 0.16 mg.L-1. Interferences of 30 diverse materials were examined. The method has been applied to the determination of oxalate in biological samples with satisfactory results.