Intercomparison program of lead, mercury, and cadmium analysis in blood, urine, and aqueous solutions.

Sixty-six European laboratories participated in an intercomparison program of lead, mercury, and cadmium analysis in blood, urine, and aqueous solutions. The experimental protocol was designed in such a way that the effect of precision, experience, and analytical method could be evaluated. For all the analyses, the scatter of the reported results is important. The major factor influencing the variability of the results is the intralaboratory variation. Analytical methods and degree of experience do not seem to have a significant influence. However, with the exception of mercury determination in urine, a satisfactory intralaboratory precision is not sufficient to make the interlaboratory variation acceptable. It appears that systematic errors are responsible for the high interlaboratory variation observed between "precise" laboratories.