DETERMINATION OF THIAMINE (VITAMIN-B1) BY INSITU SENSITIZED PHOTOCHEMICAL SPECTROFLUOROMETRY

An in situ photochemical spectrofluorimetric flow-injection method for the determination of thiamine (vitamin B1) is proposed. It is based on the conversion of thiamine in alkaline medium into an intensively fluorescent compound. The photochemical reaction is sensitized by acetone. The determination can be carried out by measuring the fluorescence intensity when the fluorescent signal reaches its maximum or at a fixed time. The calibration graph was linear up to 10.0 mug ml-1 thiamine (r = 0.9996), the limit of detection was 0.46 ng ml-1 thiamine and the relative standard deviation was 1.5% for 50.0 ng ml-1 thiamine (n = 6). The kinetic behaviour of the reaction and the effects of some experimental conditions were investigated and are discussed in detail. The mechanism of the sensitization of acetone was examined. Its application to vitamin B1 tablets and injections was found to be satisfactory. By use of a selection valve and combination with a synchronous fluorescence technique, vitamin B1, B2 and B6 in pharmaceuticals were simultaneously determined.