Determination of atmospheric Hg by collection on iodated carbon,acid digestion and CVAFS detection |
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Authors: | Nicolas S Bloom Eric M Prestbo Björn Hall Eric J Von Der Geest |
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Institution: | 1. Frontier Geosciences Inc., 414 Pontius N, 98109, Seattle, WA, USA
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Abstract: | An established industrial monitoring technique has been refined to allow the accurate determination of total gaseous Hg in air at background levels (1–3 ng·m?3). Samples are collected under vacuum through a commercially available iodide-impregnated carbon trap. For analysis, the trap is digested in a 7∶3 (v/v) mixture of HNO3+H2SO4, and an aliquot of the digest analyzed by SnCl2 reduction, dual gold amalgamation, and cold vapor atomic fluorescence spectrometric (CVAFS) detection. The traps exhibit little breakthrough (<5%) under flow rates of up to 1.0 l·min?1 for periods up to 10 days. The mean value for the blank on the half traps was found to be 0.40±0.16 ng (n=20), resulting in a 3 α detection limit of 0.07 ng·m (1 week sample at 1.0 L·m?3). Replicate field collections show a between-trap RSD of ± 6.4%, while field intercomparison with gold trapping resulted in 104±20% recovery in the 1–4 ng/m3 concentration range. |
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