Mercury speciation and analysis in drinking water by stir bar sorptive extraction with in situ propyl derivatization and thermal desorption–gas chromatography–mass spectrometry

A method for mercury analysis and speciation in drinking water was developed, which involved stir bar sorptive extraction (SBSE) with in situ propyl derivatization and thermal desorption (TD)–GC–MS. Ten millilitre of tap water or bottled water was used. After a stir bar, pH adjustment agent and derivatization reagent were added, SBSE was performed. Then, the stir bar was subjected to TD–GC–MS. The detection limits were 0.01 ng mL−1 (ethylmercury; EtHg), 0.02 ng mL−1 (methylmercury; MeHg), and 0.2 ng mL−1 (Hg(II) and diethylmercury (DiEtHg)). The method showed good linearity and correlation coefficients. The average recoveries of mercury species (n = 5) in water samples spiked with 0.5, 2.0, and 6.0 ng mL−1 mercury species were 93.1–131.1% (RSD < 11.5%), 90.1–106.4% (RSD < 7.8%), and 94.2–109.6% (RSD < 8.8%), respectively. The method enables the precise determination of standards and can be applied to the determination of mercury species in water samples.