Field analysis of mercury in water, sediment and soil using static headspace analysis

We developed a field screening method for the rapid analysis of mercury (Hg) in water, soil and sediment which can be applied cost-effectively at Hg-contaminated sites. The samples are chemically pretreated in ordinary containers, followed by analysis of the sample headspace Hg vapor using a portable commercially-available analyzer. Mercury in water samples is reduced directly by the addition of stannous chloride, while solids are first digested with aqua regia or piranha solution to liberate the Hg from the solids. Aided by vigorous agitation after addition of the reductant, the elemental Hg partitions between the solution and headspace according to Henry's Law. The method requires about 2 and 15 minutes to complete for water and solids, respectively. The method provides very useful detection limits for water (0.1 mu g/L) and solids ( less than or equal to 2 mu g/g). Intercomparisons with laboratory-analyzed environmental samples have shown reasonable agreement.