ERM-CA400 : How to ensure the reliability of mercury analysis in seawater
The JRC released a new seawater reference material certified for its mercury concentration. This certified reference material (CRM) was produced in support of the Water Framework Directive (Directive 2000/60/EC) and will make the quality assessment of coastal waters more reliable.
Because of its acute and chronic toxicity, mercury is included in the list of priority substances to determine the good chemical status of the aquatic environment (Water Framework Directive 2000/60/EC). The daughter Directive 2013/39/EU sets an Environmental Quality Standard of 70 ng/L of mercury (this amount would be equivalent to 1 lump sugar (cube) dissolved in 14 Olympic swimming pools). Measurements at such low concentrations are very challenging. To ensure that the results from environmental monitoring are reliable, Directive 2009/90/EC states that laboratories must demonstrate their competence and need to use reference materials.
To support the measurement community, the JRC produced ERM®-CA400, a certified reference material (CRM. Seawater was collected from The Netherlands and spiked with mercury to obtain a concentration of approximately 1/3 of the Environmental Quality Standard. The homogeneity and stability studies demonstrated that the material is sufficiently homogeneous and stable to act as a reference in environmental monitoring. Subsequently, 11 expert laboratories from Europe, the USA and Canada measured the mercury concentration in the reference material. The certified value, assigned in compliance with ISO Guide 34, is based on the results of these 11 laboratories and its uncertainty contains contribution of characterisation, homogeneity and stability.
The certified reference material ERM-CA400 is primarily intended for method performance control and validation purposes (e.g. trueness estimation).
Details about material sampling, processing and certification of the certified reference material ERM-CA400 are described in detail in the certification report, available together with the certificate in the online catalogue.