Determination of urinary thiamin by the thiochrome method.

A modified procedure for the determination of thiamin in human urine by the thiochrome fluorescent method was used to examine the effects of three oxidizing agents. Urinary thiamin values obtained with the use of HgCl2 as the oxidizing agent were lower than those found with the use of either BrCN or K3Fe(CN)6. This may be due to a difference in the reactivity of interfering compounds with the specific oxidizing agent used. Recovery values were acceptable for each of these three oxidizing agents, although BrCN appears to be slightly superior. In addition to the recovery values, the linear response for the thiamin standards used in this study supports the use of a smaller resin column for the pretreatment of urine samples; this was found to be more economical and convenient to use.