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THE DEVELOPMENT OF IODINE BASED IMPINGER SOLUTIONS FOR THE EFFICIENT CAPTURE OF HG USING DIRECT INJECTION NEBULIZATION - INDUCTIVELY COUPLED PLASMA MASS SPECTROMETRY ANALYSIS
Hedrick, E J., T. G. Lee, P. Biswas, AND Y. Zhuang. THE DEVELOPMENT OF IODINE BASED IMPINGER SOLUTIONS FOR THE EFFICIENT CAPTURE OF HG USING DIRECT INJECTION NEBULIZATION - INDUCTIVELY COUPLED PLASMA MASS SPECTROMETRY ANALYSIS. ENVIRONMENTAL SCIENCE & TECHNOLOGY 35(18):3764-3773, (2001).
The goals of this research are to develop a method for measuring Hg concurrently with multiple metals at concentration levels of interest in human and dietary exposure studies using DIN-ICP/MS, and to validate the method by determining the concentration of multiple-metals plus total Hg in (1) drinking water, (2) beverages and (3) archived NHEXAS composite diet samples. A sub-objective of this work is to write a report for research planners that compares the costs and relative merits of the currently available Hg methods. This report would contain single lab data for Hg in dietary samples using ICP/MS, cold vapor atomic absorption (CVAA), and cold vapor atomic fluorescence (CVAF).
Inductively coupled plasma mass spectrometry (ICP/MS) with direct injection nebulization (DIN) was used to evaluate novel impinger solution compositions capable of capturing elemental mercury (Hgo) in EPA Method 5 type sampling. An iodine based impinger solutoin proved to be very efficient for Hgo capture and was amenable to direct analysis by DIN-ICP/MS. Hgo capture efficiency using aqueous iodine (I3-) was comparable to Hgo capture using acidified potassium permanganate impinger solutions which were analyzed by cold vapor atomic absorption (CVAA), with greater than 98% capture of Hgo in the first oxidizing impinger. Using DIN-ICP/MS, it was demonstrated for the first time that iodine can be generated just prior to impinger sampling for efficiently oxidizing Hgo and retaining it in solution as HgI42-. Due to the increased interest Hg speciation from combustion sources, and the potential for using DIN-ICP/MS for mulitple metals analyses, an impinger sampling train for gaseous Hg speciation and multiple metals analyses using DIN-ICP/MS analyses is presented. The unique feature of such a sampling train is that each impinger solution in the series is amenable to direct analysis by DIN-ICP/MS. A bituminous coal was combusted in a bench scale coal system and gaseous Hg species (oxidized and elemental) were determined using the proposed impinger train. The DIN-ICP/MS instrumental detection limit was 0.003 ppb and MDLs ranged from 0.007 - 0.116 ug/L (ppb) in a variety of impinger solutions used for Hg capture.