Basic considerations for the preparation of performance testing materials as related to performance evaluation acceptance criteria

The preparation of performance testing (PT) materials for environmental and radiobioassay applications involves the use of natural matrix materials co ntaining the analyte of interest the addition (spiking) of the analyte to a desired matrix (followed by blending for certain matrices) or a combinatio n of the two. The distribution of the sample analyte concentration in a bat ch of PT samples will reflect the degree of heterogeneity of the analyte in the PT material and/or the reproducibility of the sample preparation proce ss. Commercial and government implemented radioanalytical performance evalu ation programs have a variety of acceptable performance criteria The perfor mance criteria should take into consideration many parameters related to th e preparation of the PT materials including the within and between sample a nalyte heterogeneity, the accuracy of the quantification of an analyte in t he PT material and to what "known" value will a laboratory's result be comp ared. This manuscript discusses how sample preparation parameters affect th e successful participation in performance evaluation (PE) programs having a n acceptance criteria established as a percent difference from a "known" va lue or in PE programs using other acceptance criteria, such as the guidance provided in ANSI N42.22 and N13.30.