Development and optimization of a method for detecting low mercury concentrations in humic-rich natural water samples using a CV-ICP-MS technique

摘要

In this study a method for the determination of low total mercury (THg) concentrations in humic-rich natural water samples using cold vapor technique coupled to an inductively coupled plasma mass spectrometer (CV-ICP-MS) was developed and optimized. Instrumental parameters of the CV-ICP-MS system were optimized using experimental design software and the amount of oxidizing agent, bromine monochloride (BrCl), adjusted so as to be sufficient for the high concentrations of dissolved organic carbon (16-113 mg DOC L~(? 1)) present in the field samples analyzed in this study. Method performance was assessed using spike recovery tests and analyzing certified reference material (ERM-CA615, groundwater). The detection and quantification limits of the method were 0.7 ng L~(? 1) (3σ) and 2.2 ng L~(? 1) (10σ), respectively. The field samples were collected from eight peatland forest catchments located in eastern Finland, six of which had been harvested for a study into the potential consequences of forest harvesting on trace metal mobility. THg concentrations in unfiltered, undiluted natural water samples determined using the optimized CV-ICP-MS method were compared with concentrations determined by cold vapor atomic fluorescence spectrometer (CV-AFS) based on the EPA method 1631. The results obtained with the two different methods were in good agreement with each other (r~2 = 0.98). The CV-ICP-MS method was found to be reliable for detecting low THg concentrations in humic-rich natural waters.