Matrix Certified Reference Materials for environmental monitoring under the EU Water Framework Directive: An update

The range of CRMs for Cd, Pb, Hg and Ni continues to be appropriately large, while the lack of CRMs for the organic substances is confirmed. The CRMs applicability in the light of the WFD monitoring requirements is discussed with regard to matrix match and attributes of the certified value (traceability, uncertainty and closeness to the EQS).