ABSTRACT
Arsenic exists in atmospheric particulate matter primarily in the form of inorganic oxides and arsenates. The arsenic compounds are dissolved from the sample of particulate matter with hydrochloric acid followed by reduction of arsenic to the trivalent state with KI and SnCl2. The trivalent arsenic is further reduced to arsine, AsH3, by zinc in acid solution in a Gutzeit generator. The evolved arsine is then passed through an H2S scrubber, which consists of glass wool impregnated with lead acetate, and then into an absorber containing silver diethyldithiocarbamate dissolved in pyridine. In this solution, the arsine reacts with silver diethyldithiocarbamate forming a soluble red complex which is suitable for photometric measurement with a maximum absorbance at 535 nm (2) . This method replaces a Gutzeit treatment and a titrimetric method involving the absorption of arsine in mercuric chloride and subsequent iodometric determination (3) .
