This standard specifies two methods for the determination of vitamin B1 content in feed by fluorescence spectrophotometry and high performance liquid chromatography. Method 1 of this standard is applicable to the determination of vitamin B1 in feed raw materials, compound feeds and concentrated feeds. The quantitative limit of the method is 1 mg/kg (this method is not applicable in the presence of adsorbed thiamine or interfering substances that affect the fluorescence of thiochrome). The vitamin B 1 determined by this method includes the sum of endogenous and added amounts. Method 2 specified in this standard is applicable to the determination of compound premixed feed and vitamin premixed feed. The limit of detection for method 2 was 3 mg/kg; the limit of quantification was 15 mg/kg.