The proficiency testing programme for trace elements of the CORILA project

Both interlaboratorial trials were based on the determination of As, Cd, Cr, Cu, Fe, Hg, Pb and Zn in aqueous acidic, matrix-enriched solutions at concentrations within the ranges generally found in marine water and in sediment after chemical digestion, respectively. The proficiency of participants was assessed on the basis of the z score criterion (|z|≤2, acceptable results; 2<|z|<3, questionable results; |z|≥3, unacceptable results). In the two trials, the relevant percentages for the laboratories scoring |z|≤2 and |z|<3 were 61% and 71% and 65% and 77%, respectively. These first two proficiency tests, on the one hand, clearly pointed to the benefits the laboratories had from their participation in these exercises, and on the other hand, provided sound evidence of the need for further trials based on real environmental matrices.