Some observations on the sodium arsenate assisted oxidation of ascorbic acid by phosphomolybdic acid

Abstract A simple and direct spectrophotometric method for the estimation of ascorbic acid, at the microgram level, based on its reducing action on phosphomolybdic acid in combination with sodium arsenate, has been developed. In the pH range of 1.5 to 3.5, the determination of ascorbic acid in its pure form down to 1 μg/ml is possible. The time of reaction is 20 min and the wavelength of measurement is 710 nm. The method tolerates the presence of common ingredients usually encountered in marketed fruit juices. The method is found to be applicable to the determination of ascorbic acid in pharmaceutical preparations and marketed fruit juices. The results compare well with the standard method.