FIA SPECTROPHOTOMETRIC DETERMINATION OF THIAMINE AFTER UV-IRRADIATION

The determination of thiamine was carried out by UV-photodegradation i n a single-line flow-injection assembly. The UV-photodegradation of th iamine was carried out in the coil of the injection valve, constituted of a PTFE tubing, half of its length being helically coiled around a UV lamp. A peak with two adjoining maxima was produced by injection, c orresponding to the absorbance of the irradiated and non-irradiated sa mple. The analytical parameter is the difference between the two peaks , measured at 264 nm. The calibration graph is linear over the 1.2-30 mu g/ml range of thiamine hydrochloride in 0.1M HCl. The influence of certain admired substances was studied and the method was tested for t he determination of thiamine in tablets.