Abstract
Vitamin B_1 contents in foods are usually determined by two methods. One is the thiochrome fluorometric method (method 1) and the other is the high performance liquid chromatographic (HPLC) method with the post-column derivatization using potassium ferricyanide in sodium hydroxide solution (method 2). For vitamin B_1 content in pork, we found that the method 1 and the method 2 showed different values. Lower values were always obtained by the method 2. The reason for this difference was recognized that 2-(1-hydroxyethyl) thiamin (HET), which is able to be transformed into thiochrome by potassium ferricyanide, was omitted by the method 2. HET is an active form of vitamin B_1 and its activity is equivalent to that of thiamin. However, no HPLC method has been reported for HET. We developed, therefore, a HPLC method for simultaneous determination of HET and thiamin, based on the method 2. By the method, vitamin B_1 contents in foods can be determined easily and precisely as the sum of HET, which will be converted to thiamin equivalent, and thiamin contents.
