Thiochrome rate method

The diagnostic capabilities of IDA detection were further revealed when applying the thiochrome rate method to other matrices such as urine and cereal (13). Fluorescence spectra of samples can be rapidly obtained at different pH s or excitation wavelengths. Shifts in the maxima of emission spectra under these different conditions reveal the presence of additional fluorescent species. Spectra of potential interferents can be compared to the spectrum of the sample to confirm the presence of certain species. 

Bioassay methods include yeast fermentation polyneuritic rate of cure in rat bacterial metabolism. Physicochemical methods include thiochrome fluorescence polarography chromatography absorption in neutral and acid solutions,... 

Direct measurement of circulating thiamine concentration may be made in plasma, erythrocytes, or whole blood. The plasma (or serum) concentration is thought to reflect recent intake and is mainly unphosphorylated thiamine at low concentration (around 10 to 20nmol/L). Because the erythrocyte contains approximately 80% of the total thiamine content of whole blood,mainly as the pyrophosphate, and erythrocyte thiamine stores deplete at a similar rate to other major organs, HPLC measurement of TPP in erythrocytes is a good indicator of body stores. Typical HPLC methods include a protein precipitation step, precolumn or postcolumn formation of the fluorophore thiochrome, usually with alkaline ferricyanide and isocratic separation. The method is easily standardized with pure... 

Fluorescence Kinetic-Based Measurements. Our studies of the reaction rate determination of thiamine (vitamin Bl) will be used to demonstrate the unique capabilities of rapid acquisition of spectra in kinetic measurements. The kinetic method is based on the oxidation of thiamine by Hg + in basic solutions to highly fluorescent thiochrome (16) The initial rate, taken as the change in fluorescence signal at 444 nm that occurs in a fixed time after mixing the sample and reagents, is directly proportional to the thiamine concentration. 

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