Kinetic spectrophotometric method for the determination of silymarin in pharmaceutical formulations using potassium permanganate as oxidant.

A new simple and sensitive kinetic spectrophotometric method for the determination of silymarin in pure form and in pharmaceutical formulations is described. The method is based on the oxidation of the drug with potassium permanganate at pH 7.0 +/- 0.2. The reaction is followed spectrophotometrically by measuring the decrease in the absorbance at 530 nm. The calibration graph is linear in the range of 18-50 microg x m(-1). The method has been successfully applied to the determination of silymarin in pharmaceutical formulations. Statistical comparison of the results with the reference method shows excellent agreement and indicates no significant difference in accuracy and precision.