Colorimetric determination of ascorbic acid in pharmaceuticals and fruits using a chromium(VI)-diphenylcarbazide complex

A simple and rapid method is presented for the determination of ascorbic acid. This method is based on the reducing action of ascorbic acid, which proportionately decreases the color intensity of the Cr(VI)-diphenylcarbazide complex. The absorbance of the complex was measured at 540 nm. A linear relationship between the absorbance and concentration of ascorbic acid was found to hold well up to 3.2 mu g ml(-1). Most of the common ingredients present in pharmaceutical preparations were found to be tolerated. The method has been successfully applied to the determination of vitamin C in the pure state, dosage forms and citrus fruits.