The determination of mercury in fish

Abstract

An acid digestion method followed by cold vapor atomic absorption spectrophotometry for the determination of mercury in fish is described. Sample portions are weighed into partial reflux tubes and digested with a H₂SO₄/HNO₃ mixture. Hydrogen peroxide is added to facilitate complete destruction of organic matter. Sample digestion is performed using a Technico™ BD‐40 Block Digestor held at 265°C for up to 75 min. After digestion KMnO, is added to insure complete oxidation of Hg to Hg(II). Good precision and accuracy are observed based on replicate analyses of NBS reference materials and also spikes of CH₃Hgcl solution added to fish tissue homogenates. The detection limit is 0.01 μg Hg/g fish tissue. The concentrations of Hg in fish collected from Wisconsin vaters have generally decreased since 1970 after a Hg discharge control program was initiated by the Wisconsin Department of Natural Resources.

Key words:

• Block Digestor
• cold vapor atomic absorption spectrophotometry
• fish
• mercury
• NBS reference materials
• Wisconsin

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