Fluorimetric determination of selenium(IV) and total selenium in natural waters

Abstract

A fluorimetric method for the determination of selenium(IV) in natural waters is described. Selenium(IV) is preconcentrated by extracting its complex with ammonium 1-pyrrolidine dithiocarbamate into chloroform, and back-extracting the selenium into nitric acid. The preconcentrated selenium is complexed with 2,3-diaminonaphthalene to form 4,5-benzopiazselenol, which is determined fluorimetrically. The optimal conditions for the fluorimetric determination of dissolved total selenium in natural waters were re-examined. The required volume of sample can be reduced from 5 l to 1 l. The detection limit is about 20 pM for a 1-l sample. The imprecision is about 2% between 275 and 600 pM and 8% at 131 pM.