Improvements in the use of the formaldehyde azo reaction for vitamin B1

Abstract
1. The formaldehyde azo test for vit. B1 has been improved and extended to include a preliminary investigation of the vit. content of foodstuffs, in which color tests have been compared with biological tests. Parallel results have been obtained. 2. Certain metals in small amounts interfere with this test, and also with reactions of the Pauly type.