Neutron activation analysis (NAA) has been studied to improve the accuracy and sensitivity of the analysis of trace and ultratrace
metallic impurities in plastic materials. There are two main problems in the analysis of plastics by NAA. First the contamination
during sample preparation, especially sample crushing procedure is very serious for ultratrace analysis. Another problem is
the destruction of the sample capsule due to the pressure build-up by the gases formed during neutron irradiation. A simple
preparation technique of the sample crushing method using liquid nitrogen and reducing the capsule pressure by a pin hole
was developed to solve the above problems. Two different irradiation and seven cooling conditions were also investigated to
optimize the experimental conditions. A SRM from NIST (1632b coal) has been used to investigate the accuracy of the analysis.
More than thirty elements could be analyzed in the range of sub-ppb to percent. Samples analyzed in this work were polyethylene
and polypropylene which were made by different manufacturing procedure, and pigments. Two kinds of plastic products used for
food and drug containers were also analyzed. It was found that NAA could be a powerful technique for the analysis of metallic
impurities in plastics even though their concentrations were at ultratrace levels.