Rapid colorimetric determination of tellurium with diethyldithiocarbamate in acetone-water medium

Abstract

Tellurium forms, with sodium diethyldithiocarbamate, a colored complex soluble in the acetone-water medium. The coloration is applied to the spectrophotometric determination of tellurium, and the conditions for the determination have been studied. The complex has an absorption. maximum at about 424 mμ in the medium consisting of water and 60% (v/v) acetone. It shows constant absorbance in the pH range of 6.39.0. While the complex is unstable in the daylight, tellurium can be determined accurately and rapidly when colored glass vessel is used and the absorbance measurement is carried out avoiding ultraviolet light immediately after the color development. The calibration curve for the determination of tellurium at 420 mμ shows linearity for 120 ppm of tellurium. The molar absorption coefficient at this wave length is ca. 3200, and the sensitivity of the recommended method is 0.04γ Te/cm². In this method, the presence of Fe (III), Cu (II) or Bi gives a disturbing influence. In the presence of EDTA, however, 40 ppm of Co, Hg (II), Ni or W (VI), 200 ppm of Al or Ba, and a large amount of As (III), Ca, Cd, Mg, Mn (II), Mo (VI), Pb, Se (IV) and Zn do not disturb the determination.