A 0.5g sample is digested with aqua regia at 90ºC. The Hg in the resulting solution is oxidized to the stable divalent form. Since the concentration of Hg is determined via the absorption of light at 253.7 nm by Hg vapour, Hg (II) is reduced to the volatile free atomic state using stannous chloride. Argon is bubbled through the mixture of sample and reductant solutions to liberate and to transport the Hg atoms into an absorption cell. The cell is placed in the light path of an Atomic Absorption Spectrophotometer. The maximum amount absorbed (peak height) is directly proportional to the concentration of mercury atoms in the light path. Measurement can be performed manually or automatically using a flow injection technique (FIMS).Hg analysis is performed on a Perkin Elmer FIMS 100 cold vapour Hg analyzer.

Detection Limit (ppb)

Note: Assays are recommended for values which exceed the upper limits.