EXTRACTIVE SPECTROPHOTOMETRIC DETERMINATION OF SELENIUM(IV) USING SODIUM-SALT OF HEXAMETHYLENEIMINECARBODITHIOATE

The operating conditions for the spectrophotometric determination of selenium(IV) with the sodium salt of hexamethyleneiminecarbodithioate (NaHMICdt) as a ligand by liquid-liquid extraction technique are presented. In acidic conditions selenium forms a yellow complex with the ligand which can be extracted in toluene with an absorption maxima at 335 nm. The molar absorptivity is 4.42 x 10(3) l mol(-1) cm(-1) and the Sandell's sensitivity is 16.6 ng cm(-2). The difference in the absorbance between the blank determination and selenium(IV) sample increases linearly in the concentrations range 0.5-4.0 mg/L at pH 1.0 and 4N HCl. The stoichiometry of the complex was found to be 1:4. The proposed method is extremely sensitive, reproducible and has been satisfactorily applied to the determination of trace amount of selenium in polluted water, plant material, wheat flour and medicated shampoo.