A microbiological assay on microtitre plates of thiamine in biological fluids and foods

A microbiological method for the determination of thiamine in biological fluids and food using 96-well microtitre plates and automatic plate reader, suitable for using in routine clinical diagnosis is described. Thiamine was extracted from samples by acid digestion (acetate buffer, pH 4.5) at 110 degrees C for 20 minutes. Assay recovery and reproducibility were optimally evaluated. Results obtained from this method were compared with those obtained using traditional microbiological and HPLC methods. The values resulting from this method were more or less the same as those of the traditional microbiological method, but much higher than those of HPLC assay. However, the new assay presents many advantages: it reduces the use of serum volume, which is a main benefit for clinical analysis. It lowers also the reagent costs and increases the number of analyses as well as it is easy to perform for routine clinical laboratory.