Division 2.4.2.1 Trueness of quantitative methods

In the case of repeated analyses of a certified reference material for elements, the deviation of the experimentally determined mean content from the certified value shall not lie outside the limit ± 10 %. When no such CRMs are available, it is acceptable that trueness of measurements is assessed through recovery of additions of known amounts of the element to the unknown samples. Attention is drawn to the fact that, unlike the analyte, the added element is not chemically bound in the real matrix and that therefore results obtained by this approach have lesser validity than those achieved through the use of CRMs. Recovery data are only acceptable when they are within ± 10 % of the target value.