Determination of total Hg isotopic composition at ultra-trace levels by on line cold vapor generation and dual gold-amalgamation coupled to MC-ICP-MS.
Résumé
An online pre-concn. method was developed to directly det. Hg isotopic compns. at the ng L-1 level in liq. samples. It is based on the hyphenation of a com. available cold vapor generation dual gold amalgamation system to a multi-collector ICP-MS. This automated method supports a rapid throughput and consumes \textless100 mL of sample (20-90 mL), representing a decrease of the sample size of more than two orders of magnitude in comparison to existing off-line pre-concn. strategies. The accuracy and the precision were evaluated by the anal. of a secondary std. (UM Almad´en) and results for a Hg concn. of 5 ng L-1 were δ202Hg = -0.55 ± 0.26‰ and Δ199Hg = -0.02 ± 0.15‰ (±2SD, n = 14). The method was compared to the actual ref. technique with the anal. of 6 environmental ref. materials. Direct on line cold vapor generation and dual gold-amalgamation coupled to MC-ICP-MS demonstrates its relevant applicability for low Hg concd. environmental samples (undersized biol. samples, natural waters).