Microbiological methods of thiamine measurement in biological material

Semiautomated, microbiological methods for the determination of thiamine in a variety of biological material are presented. Thiamine content was measured in bovine, ovine and rat blood, plasma, bile, urine, duodenal fluid, liver, kidney and brain. Thiamine was extracted from samples by mild acid digestion (trans aconitate pH 4.0) at 115 degrees C for 20 min. Microbiologic assays utilizing Lactobacillus fermenti and Ochromonas danica were performed on 96-well microplates and growth, as monitored by optical density, was directly read on a microplate reader at 650 nm. Particular attention was given to the validation of the two methods in terms of accuracy, reproducibility and recovery. The microbiological methods described here are specific, sensitive, and ensure good reproducibility. The methods can be used to analyse a large number of samples rapidly and at low cost.