Abstract
A quite sensitive method for determination of arsenic in ambient particulates was described which utilized arsine generation with a sodium borohydride reduction followed by heated quartz cell atomic absorption spectrophotometry. Several wet digestion methods were also examined for the extraction of arsenic from ambient particulates, and it was concluded that digestion with HNO3/H2O2 was the most satisfactory. The procedure is as follows. A given amount of particulates sample was gently heated in concentrated nitric acid together with a small amount of hydrogen peroxide on a hot plate. After filtering an insoluble residue off, the filtrate was evaporated to dryness and dissolved in 50 ml of 0.5 mol/1 hydrochloric acid. Then take 20ml of the solution containing less than 0.3μg of arsenic, 3 ml of concentrated hydrochloric acid, 1 ml of 40% potassium iodide solution and 1 ml of 20% L-ascorbic acid solution into a reaction vessel. After displacing air by nitrogen, 2.5 ml of 3% sodium borohydride solution, or one sodium borohydride tablet was added into the reaction vessel. After 30 s, generated arsine was swept into the heated quartz cell with nitrogen gas. By the present method, (0.050.3) μg of arsenic in ambient particulates was determined satisfactorily within an error of 5%.
