A comparison of techniques for preparing fish fillet for ICP-AES multielemental analysis and the microwave digestion of whole fish

• Published in: Food additives and contaminants 2001-01, Vol.18 (1), p.19-29
• Main Authors: Moeller, Anthony, Ambrose, Richard F., Que Hee, Shane S.
• Format: Article
• Language: English
• Subjects: Animals; Biological and medical sciences; Catfishes - metabolism; Fish and seafood industries; Fish Elements Multielemental Analysis Icp Analysis Fish Digestion Microwave Digestion; Food industries; Food toxicology; Fundamental and applied biological sciences. Psychology; General aspects; Metals - analysis; Methods of analysis, processing and quality control, regulation, standards; Microwaves; Quality Control; Spectrophotometry, Atomic - methods
• ISSN: 0265-203X; 1464-5122
• DOI: 10.1080/02652030010009156

Four catfish fillet homogenate treatments before multielemental metal analysis by simultaneous inductively coupled plasma/atomic emission spectroscopy were compared in triplicate. These treatments were: nitric acid wet-ashing by Parr bomb digestion; nitric acid wet-ashing by microwave digestion; tetramethylammonium hydroxide/nitric acid wet digestion; and dryashing. The tetramethylammonium hydroxide/nitric acid method was imprecise (coefficients of variation > 20%;). The dry-ashing method was fast and sensitive but had low recoveries of 50% for spiked Pb and Al and was not as precise as the Parr bomb or microwave treatments. The Parr bomb method was the most precise method but was less sensitive than the microwave method which had nearly the same precision. The microwave method was then adapted to homogenates of small whole fish ≤3cm in length. The whole fish homogenate required more vigorous digestion conditions, and addition of more acid after the evaporative step because of the presence of less oxidizable and acidsoluble components than fillet. The whole fish homogenate was also more heterogeneous than catfish fillet. A quality assurance protocol to demonstrate homogenate uniformity is essential. The use of a non-specialized microwave oven system allowed precise results for fillet and whole fish homogenates.