Extractive spectraphotometric determination of selenium traces with bis(ethanedithioamido)-2,4-dioxo-3-oxyminopentane

Bis(ethanedithioamido)-2,4-dioxo-3-oxyminopentane (bis(EDA)DOP) is proposed as a new sensitive and selective reagent for the spectrophotometric determ ination of selenium traces. The method is based on the color reaction betwe en selenium(IV) and his(EDA)DOP on heating the mixture at 50 degrees C for 2.0 min, which is extractable in l-octanol from an aqueous medium acidic wi th respect to 2--3 mol l(-1) HCl on shaking for 1.5 min. The absorbance of the extracted species is measured at 495.0 nm and the molar absorptivity is 1.268 x 10(4) l mol(-1) cm(-1). The complex system obeys Beer's law within 0.2-15.0 mg ml(-1) in Ringbom's optimum working range of 4.36-12.02 mu g m l(-1) with a sensitivity of 2.21 ng cm(-2) for effective spectrophotometric determination of total selenium. The nature of the extracted species is ML 2 as derived by the mole ratio and slope ratio methods. The method is satis factorily applicable to the determination of total selenium in various synt hetic mixtures and other samples.