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

A neutron activation method has been developed for tile analysis of hi gh density polyethylene, low density polyethylene, polypropylene, poly ethylene terephthalate and polystyrene. Samples weighing 2-5 g were ir radiated 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 belo w 1 mg/kg. Correction factors were applied for neutron flux; variation and counting geometry. The method was validated using reference mater ial 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 c onfirmed repeatability of the method. The method was used to measure i norganic contaminants in the raw polymers and retail samples of plasti c packaging used in contact with food.