A Simple and Fast Fluorimetric Method for Thiamine (Vitamin B1) Detection by Au3+-Mediated Formation of Thiochrome

Developing an effective method for thiamine detection is of great interest in clinical analysis, food processing, and pharmaceutical industries. A hitherto unreported, simple and efficient method for thiamine detection is demonstrated in this study by using Au3+ to convert the initially non-fluorescent thiamine into intensely blue-emitting thiochrome spontaneously in alkaline condition. The formation of thiochrome was characterized and confirmed by the photoluminescence and mass spectra. The linear response region for thiamine detection was observed to be 1.0x10-9-1.0x10-3 M with a correlation coefficient of 0.994. The limit of detection was calculated to be 2.0x 10-6 M. The unique homogenous-phase Au3+-assisted fluorescence detection method as developed in this study is not only highly specific to thiamine, but also simpler and faster than the conventional spectrofluorimetric methods without the need of extra separation process of thiochrome, the addition of highly toxic ions and exogenous enzymes to accelerate the formation of thiochrome.