Comparative analytical determination of thallium in different grade minerals and ores using semimethylthymol blue

Abstract

Semimethythymol blue (SMTB) has been used for the spectrophotometric determination of micro-molar amounts of thallium(lll) at λ_max 570 nm. The composition, overall stability constant and molar absorptivity of the thallium(lll)-SMTB chelate have been determined spectrophotometrically in perchloric acid-sodium perchlorate solution (<i>p</i>H 2.5). In the thallium (lll)-SMTB system, a violet T1(SMTB) chelate is formed with log β =22.1 ± 0.1 and molar absorptivity of 4.11 x 10⁴ dm³mol^-1cm^-1 at 570 nm. Interferences due to different cations, anions and organic acids in thallium (III) determination have also been investigated. Beer's law is obeyed in the range of 0.41-3.68 ppm T1(III). The reagent has been used for the spectrophotometric determination of thallium in .different grade minerals and ores.