The determination of arsenic by electrothermal atomic absorption spectrometry after liquid—liquid extraction

Abstract

Two extraction procedures are described for determination of total arsenic in biological materials. In the first, organic matter is wet-ashed, followed by an extraction with ammonium pyrrolidinedithiocarbmate and chloroform; back-extraction is done with a solution of copper(II) chloride. The second procedure is based on an oxygen-flask combustion with absorption of the products in concentrated hydrochloric acid, followed by reduction of arsenic(V) with potassium iodide; extraction with benzene and back-extraction into 0.1 M hydrochloric acid precede the final measurement by graphite-furnace atomic absorption spectrometry. The accuracy of both methods was proved by analyzing a standrad reference material. Because the oxygen-flask combustion takes only a few minutes, this procedure is preferred for routine applications, although it is restricted to biological materials with arsenic contents of at least 0.3 μg g −1 (dry weight).