Spectrophotometric determination of tellurium after separation by coprecipitation of its trifluoroethylxanthate with naphthalene

Abstract

Tellurium reacts with potassium trifluoroethylxanthate (potassium O-trifluoroethyl dithiocarbonate) to form a water-insoluble 1 : 2 (metal to ligand) complex in the pH range 0.5–2.5. This complex is easily coprecipitated with microcrystalline naphthalene from its acetone solution. It absorbs in the range 405–415 nm; Beer's law is obeyed over the concentration range 1.5–20.0 p.p.m. of Te; and the molar absorptivity and Sandell sensitivity are 6.698 × 10³ l mol^–1 cm^–1 and 0.0185 µg cm^–2 of Te, respectively. Ten replicate determinations on samples containing 37 µg of Te gave a mean absorbance of 0.200 with a standard deviation of 0.0022 and a relative standard deviation of 1.1%. The interference of various ions was studied and optimum conditions were developed for the determination of tellurium in various copper-tellurium alloys and synthetic samples.