1970 年 90 巻 3 号 p. 257-261
Colorimetric determination of barbituric acid derivatives is made by hydrolysis with sodium hydroxide to cleave the ring and coloration with a mixed solution of dimethylglyoxime and thiosemicarbazide in hydrochloric acidity. Barbituric acid derivatives like secobarbital having a methyl group in the α-position of the side chain are hardly hydrolyzed by this method and cannot be determined. Improvement of hydrolytic condition for secobarbital was examined and it was found that pretreatment with hydrochloric acid and hydrogen peroxide markedly accelerated hydrolysis rate with alkali. This method was used to examine the method of determination. Secobarbital was heated in hydrochloric acid-hydrogen peroxide mixture for 10 minutes in a boiling water bath, hydrolyzed with alkali for 10 minutes, and then colored with dimethylglyoxime-thiosemicarbazide mixture. Measurement of absorbance of this solution at 530mμ gave a straight line in the range of 50-250μg/ml of secobarbital. This method was applied to commercial tablets of secobarbital and a good result was obtained.