NEUTRON-ACTIVATION ANALYSIS FOR THE DETERMINATION OF CONTAMINANTS IN FOOD CONTACT MATERIALS

A neutron activation method has been developed for the analysis of high density polyethylene, low density polyethylene, polypropylene, polyethylene terephthalate and polystyrene. Samples weighing 2-5 g were irradiated in a thermal neutron flux of 10(16) neutrons m(-2) s(-1) and measured with gamma ray spectrometry for 64 elements. With the method developed here over 50 elements can be detected at concentrations below 1 mg/kg. Correction factors were applied for neutron flux; variation and counting geometry. The method was validated using reference material citrus leaves (NIST) for Na, Mg, Ai, K, Ca, Mn, Cu, Sr and I, and a suite of 'in house' standards doped with Al, Cr, Co, Mg, Zn and Sb confirmed repeatability of the method. The method was used to measure inorganic contaminants in the raw polymers and retail samples of plastic packaging used in contact with food.