抄録
A spectrophotometric method was deviced, based on the fact that a mercaptide was formed with dihydrothioctic acid and p-chloromercuribenzoate, leading to a corresponding increase of the ultraviolet absorbancy in the reaction mixture. Furthermore, a colorimetric method was developed by estimating the change of visible colour density which was derived from the reaction of excess p-chloromercuribenzoate with dithizone after the above-mentioned mercaptide formation. The experimental procedures were studied. The minimum amount to be determined was about 1μg/ml. Both methods were favorably applied to the study on the stability of the thioctic acid in aqueous solution, to the determination of thioctic acid in the commercial injection, and to the separative determination of thioctic acid and dihydrothioctic acid in the mixture.
