A novel method for the determination of migration of contaminants from food contact materials

Abstract

A neutron activation method has been developed for the analysis of high density polyethylene, low density polyethylene, polypropylene, polyethylene terephthalate and polystyrene food contact plastics. The method provides determination of over 50 elements at concentrations below 1 mg kg⁻¹. This technique has now been extended to study migration from food contact materials into standard food simulants (olive oil, acetic acid, ethanol and water). Samples of plastic are irradiated in a thermal neutron flux to produce radionuclides of the elements present in the plastic. Over a period of time the radionuclides of these elements may travel from the plastic into the food simulants, and hence the migration can be determined. Gamma ray spectrometry is performed on the simulants at the end of the test to quantify the migration. Any activity present must be due only to the migration of radionuclides of elements in the plastic and nothing else. This eliminates the need for a blank determination, which is required with existing migration methods. Preliminary studies have shown that detection limits of around 0.002 mg kg⁻¹ can be achieved for Sb in a retail polyethylene terephthalate (PET) bottle. This can be compared to levels of 0.005