Determination of total mercury in seafood by cold vapor-atomic absorption spectroscopy (CVAAS) after microwave decomposition

摘要

A method was developed for determination of total Hg in seafood using 10% w/v SnCl_2 · 2H_2O and continuous flow CVAAS after microwave decomposition in closed vessels. Seafoods were decomposed with 5 mL HNO_3 and 1 mL 1% w/v Nad at 200℃, transferred to polypropylene tubes containing 3.5 mL HCl, and diluted to 50 mL with H_2O. Standards were prepared in diluent containing 10% v/v HNO_3, 7% v/v HCl, and 0.02% w/v NaCl. Potential interference by 22 elements was evaluated. Interference by Se and Au was observed. Stability of standard solutions in HNO_3, HCl and NaCl was evaluated. Stabilizing effect of chloride was demonstrated. Results for six reference materials containing 0.0371-1.59 mg/kg Hg were 86-106% of certificate values. Concentrations in 11 varieties of seafood were 0.015-1.78 mg/kg. Average recoveries of inorganic and organic Hg added to seafood were 102% and 99%, respectively; average recoveries from fortified method blanks were 100% and 97%, respectively. The limits of quantitation were 0.0022 and 0.011 mg/kg in seafoods and reference materials, respectively.