EXTRACTION–ATOMIC ABSORPTION METHOD FOR THE DETERMINATION OF ARSENIC, ANTIMONY, SELENIUM AND TELLURIUM IN GEOLOGICAL SAMPLES

Abstract

An atomic absorption method (graphite furnace) has been developed for the determination of 0.01--100 μg g-1 As, Sb, Se and Te in rocks, minerals and ores. It is based on extractive preconcentration of these elements by a mixture of hexene-1 and toluene from sulphuric--bromide solutions. Se and Te are irreversibly extracted as organometallic compounds -- products of electrophilic addition to the double bond of the olefine. In the case of As and Sb reversible extraction of molecular bromide complexes with toluene takes place.Element concentrations determined in rock reference materials (basalt, clay shale, Cu--Ni-sulphide ores, complex sulphide ore) were found to be in accordance with certified values within experimental error. Owing to the elimination of matrix element, interferences, the precision of the method (relative standard deviation varies between +/-5% and +/-20%) was found to be independent of sample composition.