THE 1993 QUASIMEME LABORATORY-PERFORMANCE STUDY - TRACE-METALS IN SEDIMENTS AND STANDARD SOLUTIONS

The assessment of the QUASIMEME laboratory-performance study for trace metals in a silty and sandy sediment is given. Data for the determina tion of the five mandatory metals (Cd, Cu, Pb, Hg and Zn) are reported along with the normalizers Al and TOC. The differences between the co ncentrations found using partial (such as aqua regia) and total (such as HF or non-destructive determinations) methods are critically evalua ted. High blank values were found to affect the long-term precision of a number of laboratories. The overall assessment for bias was made us ing the IUPAC/ISO protocol based on Z-scores. P-scores were used to as sess the precision of laboratories.