An improved colorimetric determination of thiolsulfinate

✍ Scribed by Chieko Nakata; Toshikazu Nakata; Aiko Hishikawa

• Publisher: Elsevier Science
• Year: 1970
• Tongue: English
• Weight: 260 KB
• Volume: 37
• Category: Article
• ISSN: 0003-2697
• DOI: 10.1016/0003-2697(70)90262-9

✦ Synopsis

In our laboratory, Fujiwara, Yoshimura, and Tsuno (1) found a color reaction for allicin (an odor compound in garlic) or its homologs using sodium nitroprusside.

Though it has become possible to distinguish thiolsulfinate from disulfide by this reaction, it was not available for quantitative determination because of the fugitive color. In 1959, according to the color test for thiols reported by Benesch et al. ( 2), Carson and Wong (3) found that addition of a solution of N-ethyl maleimide in isopropyl alcohol, followed by potassium hydroxide in the same solvent, to thiolsulfinate yielded a pink to red color. In 1963, Schwimmer and Mazelis (4)) and in 1966 Watanabe and Komada ( 5)) reported a quantitative method for the determination of thiolsulfinate using this color reaction. It is certain that the investigation of the chemistry of allicin or its homologs has been made easier by these reports.

However, in the course of studying allicin with this reaction, the authors found the results unreliable owing to the relatively unstable color, as already recognized by Carson and Wong. In trying to eliminate this weakness of the color reaction, the authors found that addition of Lascorbic acid enhanced the stability of the color and gave satisfactory results. The present report reveals an improved method applying our finding. REAGENTS 1. 0.05M N-ethyl maleimide in isopropyl alcohol. Keep in the refrigerator.