Determinations of Total Mercury in Drinking Water and of Methylmercury in Air by Graphite-Furnace Atomic Absorption Spectrophotometry Using 2,3-Dimercaptopropane-1-sulfonate as a Complexing Agent

Abstract

The mercury (5 - 100 ng of Hg²⁺ and/or CH₃Hg⁺) in drinking water (25 ml) containing 2,3-dimercaptopropane-1-sulfonate (DMPS, 15 µg) and sodium acetate buffer (1 mmol, pH=6.0) was concentrated on two Sep-Pak C₁₈ cartridges in series. The mercury-DMPS complex was then eluted with methanol and adjusted to 2.00 ml. A portion (50 µl) was introduced into a graphite cuvette and was atomized according to a temperature program. The method detection limit (3 σ) was 0.053 μg/l; the calibration graphs were linear up to 4.00 μg/l. Accuracies of 97.4 - 99.3% were obtained when testing a synthetic natural water standard (Standard Reference Material 1641c). The proposed method could be applied to the determination of methylmercury in air with a detection limit of 1.3 ng.