A selective optosensor for UV spectrophotometric determination of thiaminein the presence of other vitamins B

A flow-through UV-photometric sensor for the rapid, sensitive and selective determination of thiamine in the presence of riboflavin, pyridoxine and hy droxocobalamine was developed. The active solid phase of the optosensor was the cationic resin Sephadex CMC-25 placed in a quartz how cell of 1 mm of optical path length. Thiamine was transitorily retained on this active micr ozone and its intrinsic absorbance monitored at 247 nm. Three calibration l ines were constructed by using 300, 600, and 100 mu l, respectively of inje cted sample volume. Their linear dynamic ranges were 2.0-33.0, 1.0-20.0 and 0.6-12.0 mu g ml(-1) and their RSD (%) 0.8, 0.9 and 1.8 for the determinat ion of 28, 15 and 9 mu g ml(-1), respectively, with sampling frequency of 1 8, 16 and 14 h(-1). The chemicals of the B-complex commonly found along wit h thiamine were tolerated at w/w ratios higher than 10, so they did not cau se interference at the usual concentrations. The sensor was successfully ap plied to the determination of thiamine in pharmaceuticals containing only t hiamine or other B vitamins as well. (C) 1998 Published by Elsevier Science B.V.