Agenda Item 16 CX/CF 13/7/16 February 2013 JOINT FAO ... - FAO.org

CX/CF 13/7/16 10Table X: Inter-laboratory validated methods for the determination of methylmercury in fishMethod Summary of method Principle ApplicabilityMinimumapplicablerange(mg/kg)LOD/LOQ(mg/kg)Recovery(%)RSDR(%)NoteAOAC 988.11Mercury (Methyl)in Fish andShellfishAOAC 990.04Mercury (Methyl)in SeafoodAOAC 983.20Mercury (Methyl)in Fish andShellfishOrganic interferences areremoved from homogenizedseafood by acetone washfollowed by toluene wash.Protein-bound methyl Hg isreleased by addition of HCl andextracted into toluene. Tolueneextract is analyzed for CH3HgClby electron capture GC.LC effluent is heated to produceHG vaper from organomercurycompouds. Hg vapor, togetherwith vaporized mobile phase, isdirected into water-cooledcondenser where mobile phase isliquefied. Hg vapor is swept withnitrogen into absorption cell inlight path of atomic absorbtionspectrophotometer.Organic interferences areremoved from homogenizedmaterial by acetone washfollowed by benzene wash.Protein-bound methyl Hg isreleased by addition of HCl andextracted into benzene. Benzeneextract is concentrated andanalyzed for CH3HgCl by GC.GC-ECD Fish and shellfish 0.50-2.30 Hg LOQ: 0.25 Hg 86-98 4-15 Type IILC-AAS Seafood 0.15-1.86 Hg LOQ: 0.06 Hg 94.4-99.6 10.5-18.2GC-ECD Fish and shellfish 0.15-2.48 Hg LOQ: 0.05 Hg 99-120 3-13