Abstract
Using the benzoyl peroxide-NaOH method, thiothiamine can be estimated nearly to 100% recovery in its mixture with thiamine. If thiamine is determined by the ferricyanide method in the presence of thiothiamine, the thiamine value obtained, is somewhat higher than the expected one, because thiothiamine is partly converted into thiamine in its dilute solution. Pure recrystallized thiothiamine in its freshly dissolved solution, does not yield thiochrome by the ferricyanide method and even 1 mg thiothiamine in nitrogen-saturated water yields less than 0.2% of the theoretical value. Thus thiamine is successfully estimated by the ferricyanide method if the autooxidation of thiothiamine in the mixture is avoided. Thiothiamine-analogous compounds ; α-aceto-γ-acetoxypropyl-(2-methyl-4-aminopyrimidyl-5)-methyl-dithiocarbamate (I), dihydrothiamine [3-(2'-methyl-4'-aminopyrimidyl-5')-methyl-5-β-hydroxyethyl-2,3 thiazoline] and oxo-thiamine [3-(2'-methyl-4'-aminopyrimidyl-5')-methyl-4-methyl-5-β-hydroxyethyl-thiazolone-2] are proved not to be transformed into thiochrome by the benzoyl peroxide-NaOH method. (I) is warmed with dilute hydrochloric acid and then it proves to be positive by this method ; thus thio-thiamine formation from (I) is shown. We can say the value estimated by the benzoyl peroxide-NaOH method is very reliable and characteristic for thiothiamine.
