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<p>In collaboration with industry, 24 of the most commonly used colourants with plastic food contact applications were selected. The colourants were obtained from a number of different sources and countries of origin and screened, using solvent extraction, for the presence of impurities and potential migrants. The solvent extracts were analysed using gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-mass spectrometry (LC-MS) procedures.</p>
<p>Following this initial screening, 7 colourants were selected for further investigations and suitable colourant/additive/plastic combinations were prepared for migration testing. In total, 15 different plastic/additive/colourant blends were prepared. For each plastic there were 2 blends each with a different additive. The plastics used in the testing were high density polyethylene (HDPE), low density polyethylene (LDPE), polypropylene (PP) and polyethylene terephthalate (PET). Additives were slip agents, antistats or colourant carriers (used in PET only). A third blend of plastic and colourant with no additive was also prepared to act as a control sample. In all cases the colourants and additives were incorporated into the plastic at their highest level to give the worst case values.</p>
<p>Test conditions were selected to represent the most severe conditions that the plastic would encounter in practice. In some cases, to give as much information as possible, more than 1 colourant was blended into a sample. Migration from the samples was measured both on receipt and after storage for approximately 3 months. </p>
<p>Background: The aim of this project was to systematically investigate the effect of several common additives on the migration of colourants and associated substances. In particular, where applicable, the effect of slip agents and anti-stats that are designed to ‘bloom’ to the surface of plastics was investigated.
This was a follow-on project building on work undertaken in the Food Standards Agency Project A03045, which reported on the migration of colourants and colourant impurities into food simulants. However, in order to avoid over complicating the analyses and to allow colourant related migrants to be readily identified, one variable that was deliberately not investigated in project A03045 was the effect of additives such as slip agents and anti-static. In the process of ‘blooming’ it is possible that the additives may also exaggerate the migration of other substances present, including those originating from colourants. </p>