Extraction, separation, and spectrophotometric determination of tellurium(IV) with 1-(4-bromophenyl)-4,4,6-trimethyl-1,4-dihydropyrimidine-2-thiol

A method is proposed for the extraction, separation and spectrophotometric determination of trace levels of tellurium(IV) from hydrochloric acid media with 1-(4-bromophenyl)-4,4,6-trimethyl-1,4-dihydropyrimidine-2-thiol (4-bromoPTPT) in chloroform. The yellow-colored complex absorbs at 440 nm and the system obeys Beer's law in the 1-15 ppm concentration range. The molar absorptivity and Sandell's sensitivity are 8.1x10(3) dm(3) mol(-1) cm(-1) and 16 ng cm(-2) respectively. The probable composition of the extracted species is TeL2. The interference of various ions was studied. Various parameters, such as the effects of the acidity, reagent concentration, equilibration time etc., have been established for the extractive spectrophotometric determination of tellurium(IV). The method has been applied for the determination of tellurium(IV) in various synthetic samples corresponding to alloys, and provides for the binary separation of tellurium(IV) from lead, bismuth, copper, gold, and antimony. It is also applicable for the simultaneous determination of selenium(IV) and tellurium(IV). The method is accurate, simple, rapid, and selective, and the overall process of extraction and determination takes about 15 to 20 min.