Submitted to: Talanta
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/18/2018
Publication Date: 8/21/2018
Citation: Chen, G., Lai, B., Mei, N. 2018. Reflux open-vessel digestion system can overcome volatilization loss in mercury speciation analysis. Talanta. 191:209-215. https://doi.org/10.1016/j.talanta.2018.08.052.
Interpretive Summary: Loss of volatile mercury in open-vessel digestion is a serious concern in seafood analysis. Such loss can be minimized without a condenser by suppressing effervescence. Two open-vessel digestion protocols were developed using low cost block heater for quantification of organic and inorganic mercury in seafood. Major digestion parameters including reagents, temperature, and time were optimized. Inorganic mercury was quantified by vapour generation; total Hg was quantified after organic mercury was oxidized to inorganic form. This high-sensitivity method was validated and applied to seafood analysis.
Technical Abstract: Loss of volatile analytes in open-vessel digestion is a serious concern for mercury speciation analysis in seafood. Such loss can be overcome by using a condenser. In this work, the need for a condenser was investigated by optimizing its dimensions. It was found that analyte loss can be minimized without a condenser by suppressing effervescence in an oxidizing medium. Two open vessel digestion protocols were developed using low cost block heater for quantification of Hg++ and total Hg in seafood. Major digestion parameters were optimized including reagents, digest temperature, and time. Hg++ was selectively reduced by SnCl2 to Hg0 and detected by atomic fluorescence spectrometry; total Hg was quantified after MeHg+ was oxidized to Hg++. MeHg+ was calculated from the difference. The method was validated using certified reference materials and applied to Hg speciation analysis in seafood with 0.20 ng g-1 limit of detection.