A method was validated for the determination of total Hg in fish muscle using continuous flow cold vapour atomic absorption (CVAAS) after microwave digestion in closed vessels. The method was validated according to European Union Regulations 333/2007 and 657/2002, considering the maximum
level for the metal in fish, established by European Union regulation 1881/2006. The procedure for determining linear range, selectivity, recovery, precision, trueness, decision limit (CCα), detection capability (CCβ), measurement uncertainty and robustness of the
method is reported. The results of the validation process demonstrate the method fulfils the provisions of the Commission Regulation. The selectivity study indicated that there was no matrix effect on the calibration curve between the concentration range of 1.0 and 30.0 µg Hg l−1.
The mean recovery calculated at six levels of fortification was in the range of 94–104%. The limit of detection (LOD) and limit of quantification (LOQ) values were 4.90 and 15.7 µg kg−1, while the CCα and CCβ values were 0.517
and 0.533 mg kg−1, respectively, for the maximum contaminant level of 0.500 mg kg−1. The relative expanded measurement uncertainty of the method was 0.055 mg kg−1. The method was not affected by slight
variations of some critical factors (ruggedness minor changes) as sample mass and volume of the HNO3 and H2O2 used in the digestion step. The method allowed accurate confirmation analyses of the CRM DORM 3®. In fact, the Z-scores attained in a proficiency
test round were well below the reference value of 2.0, proving the excellent performance of the laboratory.
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heavy metals – mercury;
metals analysis – AAS
Document Type: Research Article
Laboratory of Residues and Contaminants, National Laboratory of Ministry of Agriculture, Livestock and Food Supply (LANAGRO-PA), Brazil, Av. Almirante Barroso, 1234, 66095-000, Brazil
April 1, 2012