SIMULTANEOUS EXTRACTION OF TRIVALENT AND PENTAVALENT ANTIMONY AND ARSENIC SPECIES IN NATURAL-WATERS FOR NEUTRON-ACTIVATION ANALYSIS

Antimony(III) and arsenic(III) in aqueous sample can be simultaneously extracted with ammonium pyrrolidinecarbodithioate (APCDT) into chloroform from pH 3 to 6. Extraction of antimony(V) and arsenic(V) can be achieved by reduction with thiosulfate and potassium iodide at pH 1 followed by APCDT extraction at the same pH value. The Sb- and As-PCDT complexes in the organic phase can be back-extracted into a nitric acid solution for neutron activation analysis (NAA). Detection of 10-3 .mu.g/L of antimony and arsenic can be achieved by using this extraction method and NAA. Applications of this method to antimony and arsenic speciation studies in natural water systems are discussed.