Implementation of flow-through solid phase spectroscopic transduction with photochemically induced fluorescence: determination of thiamine

For the first time, flow-through solid phase spectroscopic transduction has been implemented with photochemically induced fluorescence. The system developed allows the sensitive, selective and rapid determination of thiamine in the presence of the rest of B-complex vitamins. By UV-irradiation in a single-line flow injection device, thiamine is converted on-line into a strongly fluorescent photoproduct, which is retained on C18 silica gel filling the flow cell placed in the detector. The fluorescence of the photoproduct retained on C18 is measured at excitation and emission wavelengths of 367 and 443 nm, respectively. The sorption of the photoproduct on the solid support improves noticeably sensitivity and selectivity with regard to previously reported photochemical-fluorimetric methods. Two calibration lines are constructed for 300 and 600 μl of injection volume. Concentrations of the vitamin of 0.18-80 ng ml−1 (300 μl) and 0.09-50 ng ml−1 (600 μl) are determined; the detection limits are 55 and 28 ng l−1 and the R.S.D.s are 1.4 and 2.4%, respectively. The method allows the analysis of 52 and 36 samples per hour, respectively. The applicability of the method for the determination of thiamine in pharmaceuticals and human serum and urine was demonstrated by investigating the effect of potential interferences and by the analysis of real samples. The accuracy of the proposed method was checked by applying a reference method and a recovery test. Recovery levels were between 95 and 105%.