Fluorometric Determination of ppt Level Selenium (IV) in Sea Water by Thorium Hydroxide Coprecipitation Method

Abstract

A new coprecipitation method for the fluorometry of selenium (IV) in sea water has been developed.Selenium (IV) was coprecipitated with thorium (IV) hydroxide from 1,000 ml of sea water at pH 7.0.Without aging, the precipitate was centrifuged and then dissolved in hydrochloric acid. Selenium (IV) with the thorium was determined by the usual fluorometry with 2, 3-diaminonaphthalene, because theinterfering thorium (IV) ions were masked by EDTA and sodium fluoride. This method was applicableto groundwater samples. The concentrations of selenium (IV) in coastal sea water and groundwater were in the range of 21.6-23.7 ng/l and 39.5-54.4 ng/l, respectively.