The gas chromatographic determination of selenium(IV) and total selenium in natural waters with 1,2-diamino-3,5-dibromobenzene

Abstract

The total selenium and selenium(IV) contents in sea water and river water can be determined directly by a gas chromatographic method with l,2-diamino-3,5-dibromobenzene without preconcentration. The reagent reacts only with selenium(IV) to form a 4,6-dibromopiazselenol; other oxidation states of selenium must therefore be converted to the tetravalent state for total selenium determinations. The piazselenol formed can be extracted quantitatively into 1 ml of toluene from 500 ml of sample water. A method is proposed for the determination of selenium(IV) and total selenium in natural waters at levels as low as 2 ng l^-1. Coastal sea water and river water in Japan contain 8–30 ng of Se(IV) and 20–50 ng of total Se per liter.