Differential Determination of Selenium(IV) and Selenium(VI) in River Water by Hydride Generation Inductively Coupled Plasma Atomic Emission Spectrometry

Abstract

Selenium(IV) and selenium(VI) in river water were determined differentially by hydride generation inductively coupled plasma atomic emission spectrometry. Selenium(IV) in the water was extracted with 4-nitro-o-phenylenediamine into toluene as 4-nitropiazselenol. The extract was concentrated by evaporation, decomposed with nitric and perchloric acids, and reduced with concentrated hydrochloric acid. The total selenium was determined by digesting the water with nitric, sulfuric and perchloric acids and reducing the selenium with concentrated hydrochloric acid. The interfering transition metals were eliminated by elution with Chelex 100 chelating resin. The siliceous residues deposited during the digestion were dissolved with hydrofluoric acid. The selenium(VI) content was estimated by subtracting the selenium(IV) content from the total selenium. The detection limit (3 times the signal to noise ratio) for both the total selenium and selenium(IV) with 500 ml water samples were 0.03 ng ml^-1. The relative standard deviations of the total selenium and selenium(IV) were 4.2 and 17.2%, respectively.