Abstract
Three commercially available filtering media were evaluated for the collection of airborne particulates of the organoarsenicals monomethylarsonic-acid (124583) (MMA), dimethylarsenic-acid (144218) (DMA), and p-aminophenylarsonic-acid (APA). Filtering media tested were 0.8 micrometer (microm) pore size cellulose ester membranes, 1microm pore size Fluoropore, and 5microm pore size Mitex. Ion exchange chromatography followed by continuous generation of the arsine derivatives and atomic absorption were used for separation and analysis of the compounds of interest. The contribution of vapor forms of organoarsenicals to the total atmospheric concentration was also examined. MMA, DMA, and APA were placed in an impinger heated to 122 degrees-F, and air drawn over them was sampled for total arsenic content. The extent to which any organoarsenical vapors were generated was below the analytical detection limits, so only particulate forms of these compounds were sought further. Filters were spiked with MMA, DMA, APA, arsenic(III) and arsenic(V), allowed to dry, extracted ultrasonically in deionized water or acid or basic medium and stored and analyzed over a period of 1 week. Filters were then spiked with combinations of the organoarsenicals and analyzed against calibration standards. Mixed aerosols containing the organoarsenicals were generated and collected to test collection efficiency. Effects of high temperature and 95 percent relative humidity were also examined. Filter extracts changed drastically unless stored in acetate or borate buffers under refrigeration. Percent recoveries from cellulose ester filters were poor, 62 to 78 percent, while they exceeded 90 percent for Fluoropore and Mitex. Collection efficiency of the Fluoropore filters was better than 99 percent while that of Mitex was about 65 percent, due to the large pore size. No significant effects of temperature or humidity were demonstrated. The authors conclude that the efficiency of the Fluoropore filters is as good as the traditionally used cellulose ester filters and in addition, Fluoropore filters are inert towards the various organoarsenical species.
