Thesis (M.Sc.)--Chulalongkorn University, 2004

The use of diluted acid to extract lead, chromium, cadmium, copper and zinc from seafood was a solid-liquid extraction procedure with atomic absorption spectrometry. Ultrasonic-assisted acid leaching extraction technique was attempted for the multi-elemental analysis of seafood (mussel and fish) samples. The effects of several parameters: nitric acid concentration, hydrochloric acid concentration, hydrogen peroxide concentration, acid solvent volume, sonication time and temperature have been studied. A 30-minute sonication, 56 degree celcius operating temperature and 6 mL of 3.7 M HNO3/3.7 MHCI/0.5 M H[subscript2]O[subscript2] of 1:1:1 ratio as acid solvent were used. The results obtained by the proposed procedure were evaluated by comparison with the results obtained by microwave-assisted digestion. %Ratio of metal amount obtained from leaching technique to amount determined by digestion technique for cadmium, copper and zinc ranged from 92-114% andfrom 88-103% for fish and mussel samples, respectively. Whilst, chromium and lead were not leachable from both samples by this condition. The MDL were 0.08, 0.02, 0.13 and 0.63 mg/kg for lead, cadmium, copper and zinc, respectively. The accuracy of the developed method was test by analyzing DORM-2, Dogfish Muscle certified reference material. Found values from acid leaching technique and digestion technique of cadmium were higher than certified values. %Recoveries for zinc and copper were in the order of 80 to 87%