title: Simple analysis of total mercury and methylmercury in seafood using heating vaporization atomic absorption spectrometry.
abstract: This study aimed to develop a simpler method for determining total mercury (T-Hg) and methylmercury (MeHg) in biological samples by using methyl isobutyl ketone (MIBK) in the degreasing step. The fat in the samples was extracted by MIBK to the upper phase. T-Hg transferred into the water phase. This was followed by the extraction of MeHg from the water phase using HBr, CuCl2 and toluene. The MeHg fraction was reverse-extracted into L-cysteine-sodium acetate solution from toluene. The concentrations of T-Hg and MeHg were determined by heating vaporization atomic absorption spectrometry. Certified reference materials for T-Hg and MeHg in hair and fish were accurately measured using this method. This method was then applied to determine T-Hg and MeHg concentrations in the muscle, liver and gonads of seafood for the risk assessment of MeHg exposure. The mean T-Hg and MeHg concentrations in squid eggs were 0.023 and 0.022 µg/g, and in squid nidamental glands 0.052 and 0.049 µg/g, respectively. The MeHg/T-Hg ratios in the eggs and nidamental glands of squid were 94.4% and 96.5%, respectively. The mean T-Hg and MeHg concentrations in the gonads of sea urchins were 0.043 and 0.001 µg/g, respectively, with a MeHg/T-Hg ratio of 3.5%. We developed an efficient analytical method for T-Hg and MeHg using MIBK in the degreasing step. The new information on MeHg concentration and MeHg/T-Hg ratios in the egg or nidamental glands of squid and gonads of sea urchin will also be useful for risk assessment of mercury in seafood.
authors.affiliation: Department of Basic Medical Science, National Institute for Minamata Disease.
authors.forename: Keisuke
authors.initials: K
authors.lastname: Yoshimoto
authors.forename: Hoang Thi Van
authors.initials: HT
authors.lastname: Anh
authors.forename: Atsushi
authors.initials: A
authors.lastname: Yamamoto
authors.forename: Chihaya
authors.initials: C
authors.lastname: Koriyama
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Ishibashi
authors.forename: Masaaki
authors.initials: M
authors.lastname: Tabata
authors.forename: Atsuhiro
authors.initials: A
authors.lastname: Nakano
authors.forename: Megumi
authors.initials: M
authors.lastname: Yamamoto
mesh_terms: D000818:Animals; D001822:Body Burden; D002138:Calibration; D049832:Decapodiformes / Q000737:chemistry*; D005399:Fishes; D005506:Food Contamination; D005523:Food Supply; D006066:Gonads / Q000737:chemistry; D008099:Liver / Q000737:chemistry; D008767:Methylmercury Compounds / Q000032:analysis*; D009132:Muscles / Q000737:chemistry; D012015:Reference Standards; D012617:Sea Urchins / Q000737:chemistry*; D017747:Seafood / Q000032:analysis*; D013054:Spectrophotometry, Atomic / Q000592:standards; D014835:Volatilization; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D008767:Methylmercury Compounds; D014874:Water Pollutants, Chemical