Determination of selenium in organic selenium compounds by ion chromatography

This paper describes a simple and sensitive method for determining selenium in organic selenium compounds by ion chromatography with an oxygen-flask-combustion method. An anion-exchange column packing with porous poly(vinyl alcohol)gel (Shodex IC IF-424, 4.6 mm i.d. × 100 mm) is installed in an ion chromatograph equipped with an anion micromenbrane suppressor and a conductometric detector. 1.5mM sodium carbonate and 2.0 mM sodium bicarbonate are the optimal mobile phase for the simultaneous determination of a mixture of 9 anions (F-, Cl-, NO2-, Br-, NO3-, HPO42-, SeO32-, SO42- and SeO42-) under the following conditions: flow rate, 1.0 ml/min; scavenger, 12.5 mM H2SO4; column temperature, 30°C. Several mg of sample are burned in an oxygen flask filled with 20 ml of water as an absorbent, and water is added to make 200 ml. A 50 μl aliquot of a sample solution is injected into the column. The content of selenium by this method is in good agreement with that calculated from the molecular weight within a relative error of 2%. It was found that selenium in an absorbent from the combustion of a sample exists only in the selenite form.