Collaborative study to improve the quality control of rare earth element determinations in environmental matrices

In order to control the quality of rare earth determinations in environment al matrices, the Standards, Measurements and Testing Programme (formerly Co mmunity Bureau of Reference, BCR) of the European Commission has started a project, the final aim of which is to certify four types of matrices (tuna muscle, mussel tissue, aquatic plant and estuarine sediment) for their cont ents of a range of rare earth elements (Sc, Y and the lanthanides: La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu). The elements U and Th w ere added to the study. The first part of this project consisted of an inte rlaboratory study which aimed to test the feasibility of preparation of env ironmental reference materials and to detect and remove most of the pitfall s observed in rare earth determinations. This paper presents the preparatio n of the four matrices for the intercomparison study and for the candidate reference material. The main results are presented of the interlaboratory s tudy that was carried out prior to the certification campaign. This collabo rative trial is the first attempt ever carried out at this scale to evaluat e the state-of-the-art of rare earth determinations in the environment. Its impact on the improvement of chemical measurements will have positive effe cts on the comparibility of data necessary for environmental monitoring.