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R9 Laboratory SOP 515
DETERMINATION OF MERCURY IN WATER BY COLD VAPOR ATOMIC ABSORPTION SPECTROMETRY
Summary
This SOP describes the instrumental analytical procedures for mercury by cold vapor atomic absorption (CVAA). This method is applicable for drinking, ground, surface, sea and brackish water, domestic and industrial wastes. This method applies to the determination of total mercury (organic + inorganic) by EPA Method 245.1 using the Leeman PS200 Mercury Analyzer for high level samples and the CETAC M6000A Mercury Analyzer for drinking water samples. Sample and standard preparation procedures for both mercury analyzers are described in Region 9 Laboratory SOP 415.
The quantitation limit (QL) is 0.2 mg/L for total mercury analyzed using the Leeeman PS200; the QL is 30 ng/L for total mercury analyzed using the CETAC M6000A.
An aliquot of a water sample is transferred to a BOD bottle or equivalent closed-system container. The sample is digested with a dilute potassium permanganate-potassium persulfate solution for two hours at 95°C. The digestion oxidizes all forms of mercury to Hg(II). The Hg(II) in the digested water sample is reduced with stannous chloride to elemental mercury which is sparged from the sample and detected by atomic absorption. The measurement step is performed using an automated mercury analyzer.