Evaluation of an interlaboratory proficiency-testing exercise for total mercury in environmental samples of soils, sediments and fish tissue

A proficiency-testing scheme concerning total mercury determination in soils and sediments (with different levels of contamination) and fish tissue involved 25 European laboratories as participants, who used their regular in-house analytical methods, and reference values were determined from the results obtained. The most precise results were obtained for the fish matrix. The majority of participants obtained satisfactory Z-scores, and laboratories that need to revise their procedures were singled out. When compared with performances in other previous interlaboratory exercises for total mercury, the overall performance of participants may be considered satisfactory, and the ability to produce results of acceptable quality for mercury appears to be improving.