Spectrophotometric flow injection determination of trace amounts of thallium with 4-(4′-N,N-dimethylaminophenyl) urazole as a new reagent

A simple, sensitive, rapid and selective method is proposed for the flow injection determinations of thallium by spectrophotometric detection. The method is based on the oxidation of 4-(4-N,N-dimethylaminophenyl) urazole (DAPU) to the corresponding triazolinedione (TAD) by Tl(III) at pH 4.0. The reagents and manifold variables influences on the sensitivity were investigated and the optimum conditions were established. Thallium can be determined from the range of 8.0 x 10(-8) - 3.0 x 10(-5) M Tl( III) and a detection limit of 5.0 x 10(-8) M was obtained with a sample rate of 20 +/- 5 samples/ h. The relative standard deviations for five replicate determination of 5.0 x 10(-6) and 1.0 x 10(-5) M were 2.75 and 1.96%, respectively. The proposed method was used to determination of thallium in real samples with satisfactory results.