The French interlaboratory quality assessment programme for copper, zinc and selenium in blood serum.

The group for quality assurance for trace elements of the Société Française de Biologie Clinique (SFBC) has operated an interlaboratory quality assessment programme for copper, zinc and selenium determinations in blood serum since 1988. The primary objective is to enable participants to maintain or improve the accuracy of their analytical performances by comparing their results with other laboratories, every two months, on the basis of three quality criteria: comparison to the mean value, recovery of added copper, zinc and selenium, between-run reproducibility for identical samples. A further aim of this scheme is to evaluate interlaboratory transferability of the results. The procedure for individual and overall evaluation is reported. For each participant a performance score is calculated for each quality criteria, and a global score is attributed. The analytical performances of the participants were considered "good", "acceptable" or "inadequate" according to their global scores. Some of the results observed in this scheme are interpreted on the basis of differences between the notions of quality control and total quality assurance.