Development of Reference Material of Mercury in Fish: A comparison of different alternatives to homogeneity assessment

Leonardo Soto, Niño Fabian, Diego A. Garzón, Diego A. Ahumada

Abstract

A candidate to certified reference material for mercury in fish was produced from Calophysus macropterous, a species of catfish that has been reported with high levels of this contaminant at the Amazonian region. The fish was filleted, freeze-dried and degreased, then sieved, homogenized and packaged; 106 bottles were produced with a net content of 15 g. In the study of homogeneity of the material, ICP-MS in standard mode was used, like a measurement method with microwave-assisted acid digestion. The homogeneity assessment with a random sampling stratified was carried out. The preparation and measurements of the samples were carried out using microwave-assisted digestion and ICP-MS. The current study involved the evaluation of different isotopes (¹⁹⁹Hg, ²⁰⁰Hg, ²⁰¹Hg, ²⁰²Hg) and internal standards to correct the analytical signals. Finally, to evaluate the uncertainty due to heterogeneity, different approaches were used. The results showed that there are differences between the classic ANOVA approach and meta-analysis methods, especially when MSbetween < MSwithin. Furthermore, the most important differences were found between the uncertainties using different combinations of isotopes / internal standards, because in some cases, up to three times higher uncertainties were found.

Keywords

Homogeneity assessment, Mercury, Fish, ANOVA, Meta-analysis

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IMEKO TC

TC10 - Measurement for Diagnostics, Optimization and Control

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