Development of surfactant assisted spectrophotometric method for determination of selenium in waste water samples

Abstract

A new, simple and highly selective method for spectrophotometric determination of selenium in waste water samples is described. Selenium(IV) oxidizes I − ions into I 2 which subsequently reacts with excess of I − ion in the acidic media to give tri-iodide ions (I 3 −), and it further reacts with cetylpyridinium cation (CP +) to give a violet colored species. The value of molar absorptivity of the ion-associate species in terms of selenium is 1.80 × 10 4 L mol −1 cm −1 at λ max 510 nm. The detection limit of the method is 10 ng mL −1 Se. The calibration curve is linear over 50–1000 ng mL −1 Se with slope, intercept and co-relation coefficient of 0.23, −4.0 × 10 −4 and +0.99, respectively. None of the tested diverse ions interfered in the present method. The method has been tested for the determination of selenium in waste water samples.