Determiantion of thiamine in foods by high performance liquid chromatography with post-column photochemical derivatization and fluorescence detection

A high performance liquid chromatographic method with post-column photochemical derivation and fluorescence detection was developed for the analysis of thiamine in foods. A C-18 column was used for separation, and elution was performed with a pH 4.0 phosphate buffer (0.1 mol/L) containing 2% acetonitrile. When the eluate was on-line converged with a mixed 0.75% Na2SO3-4% NaOH solution, thiamine in the eluate was transferred to an intensive fluorescence compound by post-column photochemical derivation that occurred in a knotted polytetrafluoroethylene reactor, and detected by a spectrofluorimetor. Under optimized conditions, a detection limit of 3.8 mu g/L thiamine was achieved with the injection volume of 20 mu L, and a linear calibration curve was obtained in the range of 0.033 similar to 10 mg/L thiamine. RSD was in the level of 1.8%, and the recoveries of spiked analyte were in the range of 97% similar to 102%. The developed method was applied to determine the thiamine contents in pork liver and milk powder, and satisfactory results were obtained.