Production of certified reference materials - homogeneity and stability study based on the determination of total mercury and methylmercury

Reference materials (RMs) play an important role in all elements of the quality assurance system of measurements. In this work, "package" 4 new CRMs (bottom sediment, herring tissue, cod tissue, cormorant tissue) were prepared and characterised to carry out the quality control in monitoring analysis of mercury and methylmercury in environmental samples. Materials - candidates were collected in Poland and south part of the Czech Republic. All materials were freeze-dried, milled, sieved, homogenised, sterilized and distributed in amber bottles. For the homogeneity and stability study of the samples of materials several statistical tests were applied. Materials - candidates for CRMs with certified mercury and methylmercury content meet the heterogeneity requirement and can be considered homogenous both between bottle and within bottle. Each material meets also the requirements for the stability condition of reference material with certified mercury content.