Indirect spectrophotometric determination of ascorbic acid in pharmaceuticals

A new sensitive determination procedure for ascorbic acid was developed based on the reduction of ascorbic acid to Fe(Ⅲ) 2 〔2 (6 methylbenzothiazoly)azo〕 5 diethylaminobenzoic acid complex.In the presence of HAc NaAc buffer(pH=5 8)and SDS,the maximum absorption wavelength of the system is 635?nm and absorptivity is 2 2×10 5L·mol -1 ·cm -1 .The absorbance is directly proportional the concentration of ascorbic acid in the range of 0～0 64?μg/mL.And the proposed method was used to determine the concentration of ascorbic acid in pharmaceuticals.