Quality assessment of INAA data for small-sized environmental reference samples.

Instrumental neutron activation analysis (INAA) was applied for the accurate and precise determination of minor and trace elements in small-sized aliquants (1 to 2 mg) of two certified reference materials (CRM), NIES No. 8 and NIST 1632c. Four laboratories used either comparative- or k0-INAA, or both, and repeated the analysis more than ten times for each CRM. Based on z-scores and zeta scores of analytical data, QA/QC in analyzing such small scale of the two reference samples was assessed, revealing that there was a clear difference in the analytical ability among participating laboratories. It was concluded that the two CRM samples on the mg scale can be used as reference samples in INAA of a similarly small-scaled sample, at least for the 16-18 elements examined.