The IAEA conducted the IAEA-CU-2006-06 Proficiency Test (PT) on “The determination of major, minor and trace elements in ancient
Chinese ceramic” in 2006. The results of this PT showed that of the 21 analytes reported by our laboratory 9 failed the precision
criteria. Therefore the results reported by our laboratory along with the results of other laboratories which carried out
analysis using neutron activation analysis (NAA) were studied. It was found that the major factor contributing towards data
falling in the “Warning” category, failing the precision criteria was the high uncertainties cited in the certificates of
the reference materials (RMs) used for quantification of data. In this regard, it is recommended that synthetic standards
should be prepared and used on a routine basis especially for the measurement of the elements K, Eu, Lu, Ta, Tb and Yb.