Geologic materials are decomposed by a mixture of aqua regia and hydrofluoric acid. Arsenic is reduced to the trivalent state with potassium iodide. Interferences are minimized by the addition of SUMMARY Interferences commonly encountered in the determination of bismuth, cadmium, copper, lead, silver, and zinc at crustal abundance levels are effectively eliminated using a rapid, sensitive, organic extraction method. A potassium chloratehydrochloric acid digestion solubilizes the metals not tightly bound in the silicate lattice of rock, soil, and stream-sediment samples. The six metals are selectively extracted into an organic phase of 10 percent tricaprylylmethylammonium chloridemethyl isobutyl ketone in the presence of ascorbic acid and potassium iodide.Metals in the organic extract are determined by flame atomic absorption spectrometry to the 0.05 ppm level for cadmium and silver and to the 1. 0 ppm level for bismuth, copper, lead, and zinc. About 40 samples can be analyzed per day for the six metals. If only selected metals are determined, more samples can be analyzed.

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Arsenic, antimony, bismuth, cadmium, copper, lead, molybdenum, silver and zinc are very-useful elements in geochemical exploration. In the proposed method, geological samples are fused with potassium pyrosulphate and the fusate is dissolved in a solution of hydrochloric acid, ascorbic acid and potassium iodide. When this solution is shaken with a 1O0/o VNAliquat 336isobutyl methyl ketone organic phase, the nine elements of interest are selectively partitioned in the organic phase. All nine elements can then be determined in the organic phase using flame atomic-absorption spectrometry. The method is rapid and allows the determination of Ag and Cd at levels down to 0.1 p.p.m., Cu, Mo, and Zn down to 0.5 p.p.rn., Pb, Bi and Sb down to 1 p.p.m. and As down to 5 p.p.m. in geological materials.

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