Rapid Determination of Ascorbic Acid by Color-Fading-photometry

It was found that 1,1-diphenyl-2-picrylhydrazihydrate (DPPH) is reduced by ascorbic acid under room temperature in aqueous solution,leading to color-fading of the DPPH,and that the magnitude of decrease in absorbance of DPPH measured at its absorption maximum of 517 nm was found to keep linear relationship with the mass concentration of ascorbic acid in the range from 1.3 to 10.0 mg·L-1.Based on these facts,a rapid photometric method for determination of ascorbic acid was proposed and applied to the analysis of drug samples of Vitamin C tablets and injections,giving values of average recovery of 96.4% and 98.5%,values of RSD′s (n=6) of 1.8% and 3.7% respectively.