title: Extraction of methylmercury from tissue and plant samples by acid leaching.
abstract: A simple and efficient extraction method based on acidic leaching has been developed for measurement of methylmercury (MeHg) in benthic organisms and plant material. Methylmercury was measured by speciated isotope-dilution mass spectrometry (SIDMS), using gas chromatography interfaced with inductively coupled plasma mass spectrometry (GC-ICP-MS). Reagent concentration and digestion temperature were optimized for several alkaline and acidic extractants. Recovery was evaluated by addition of MeHg enriched with CH3 201Hg+. Certified reference materials (CRM) were used to evaluate the efficiency of the procedure. The final digestion method used 5 mL of 4 mol L(-1) HNO3 at 55 degrees C to leach MeHg from tissue and plant material. The digest was further processed by aqueous phase ethylation, without interference with the ethylation step, resulting in 96 +/- 7% recovery of CH3 201Hg+ from oyster tissue and 93+/-7% from pine needles. Methylmercury was stable in this solution for at least 1 week and measured concentrations of MeHg in CRM were statistically not different from certified values. The method was applied to real samples of benthic invertebrates and inter-laboratory comparisons were conducted using lyophilized zooplankton, chironomidae, and notonectidae samples.
authors.affiliation: Chemistry Department, Trent University, 1600 West Bank Drive, Peterborough, ON, K9J 7B8, Canada. hhintelmann@trentu.ca
authors.forename: Holger
authors.initials: H
authors.lastname: Hintelmann
authors.forename: Hong T
authors.initials: HT
authors.lastname: Nguyen
mesh_terms: D000143:Acids; D000818:Animals; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods; D006878:Hydroxides / Q000737:chemistry; D000432:Methanol / Q000737:chemistry; D008767:Methylmercury Compounds / Q000302:isolation & purification*; D010944:Plants / Q000737:chemistry*; D017680:Potassium Compounds / Q000737:chemistry; D015048:Zooplankton / Q000737:chemistry
chemical_list: D000143:Acids; D006878:Hydroxides; D008767:Methylmercury Compounds; D017680:Potassium Compounds; C029943:potassium hydroxide; D000432:Methanol