2-(2-Thiazolylazo)-p-cresol (TAC) as a reagent for the spectrophotometric determination of indium(III)

Abstract

The reaction between indium(III) and the 2-(2-thiazolylazo)-p-cresol (TAC) in aqueous methanol media at apparent pH 5.0–6.0 results in an intensely colored complex which is stable for at least 2 h. The composition is 1:2 cation: TAC and the log of the formation constant is 10.78 ± 0.64. Beer's law is obeyed up to 8.0 μg · ml−1 of indium(III) at 580 nm. The apparent molar absorptivity at 580 nm is 1.21 × 104 liter · mol−1 · cm−1 and the detection limit was obtained as 10.0 ng · ml−1 of indium(III). The method is applied to the determination of indium in a catalyst.