Selective spectrophotometric determination of periodate based on its reaction with methylene green and its application to indirect determination of ethylene glycol and glycerol

Abstract: A rapid, simple, accurate, and highly selective spectrophotometric method is proposed for the determination of periodate in water samples. This method is based on the reaction of methylene green with periodate in the presence of iodide. The decrease in the absorbance of methylene green is used to monitor the reaction spectrophotometrically at 613nm. Under the optimum conditions, periodate could be determined in the concentration range 0.18–6.0μgmL−1. The detection limit for the method is 0.010μgmL−1. The influence of various foreign species was studied, and it was found that iodate did not interfere with the determination even in the presence of 200-fold of periodate. The relative standard deviations for six replicate determinations of 0.30, 0.50, 1.0, 1.5, 4.0, and 5.5μgmL−1 of periodate were 3.33, 2.0, 1.6, 1.33, 0.50, and 0.55%, respectively. The proposed method was applied to the determination of periodate in water samples and indirect determination of ethylene glycol in antifreeze and glycerol in vegetable oil via malaprade reaction, and satisfactory results were obtained. [Copyright &y& Elsevier]