Feasibility of Using AAS for the Characterization of a Tuna Fish Candidate Reference Material for Total Hg and Methyl-Hg Measurement

Abstract

This work describes the evaluation of several parameters for preparing a tuna fish candidate reference material (RM) in order to measure its total Hg and methyl-Hg mass fractions by cold vapor atomic absorption spectrometry (CV-AAS) and solid sampling graphite furnace atomic absorption spectrometry (SS-GF AAS). Best results were acquired after extraction with toluene and L-cysteine for 15 min at 80 degrees C. The parameters investigated were stability of chemical composition during production, homogeneity and analyte segregation. No analyte segregation was observed and the material was shown to be stable even when stored at 50 degrees C for 10 months. Total Hg mass fraction was 3.03 +/- 0.22 mu g g(-1) by CV AAS, 2.99 +/- 0.43 mu g g(-1) by SS-GF AAS and 2.95 +/- 0.15 mu g g(-1) by direct mercury analyser (DMA). Methyl-Hg mass fraction was 2.49 +/- 0.13 mu g g(-1) by CV AAS and 2.44 +/- 0.46 mu g g(-1) by SS-GF AAS.