Abstract
A chemical determination mothod for lipoic acid was investigated according to Hager who applied the method to the study of dihydrolipoic dehydrogenase. It was based on the reaction that sulfhydryl groups reduce ferricyanide quantitatively to ferrocyanide and the ferrocyanide formed is measured colorimetrically. The conversion of lipoic acid in samples to dihydrolipoic acid was done with 10mg of NaBH_4 and 0.3ml of 10% HCl was used in order to remove the excess of NaBH_4. Optimum amounts of lipoic acid to be determined were 5 to 50mμg in samples. This method can be applied to the determination of pure lipoic acid preparation, but it was not adequate to that of the small amount of lipoic acid in biological samples.
