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Investigations Into the Use of Overall Migration Methods to Test for Substances with High Specific Migration Limits


The aim of this project was to evaluate the possibilities and limitations of using gravimetric overall migration (OM) results to reduce the need for individual chemical analysis for the migration levels of specific substances. If for example the OM result for a plastic was numerically lower (in mg/kg units) than the specific migration limit (SML) for one or more monomers or additives used in that plastic, then there would be no need to test specifically for the migration of these substances.

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Research Approach:<br> Thirty substances were selected for testing. Already excluded at this stage were substances thought likely to be too volatile or too unstable to survive the evaporation procedure used in OM testing. Eleven of the substances were monomers and four of these gave an acceptable recovery (>70%). Nineteen of the substances were additives and fourteen of these gave an acceptable recovery. For the substances that suffered more than 30% loss, seven monomers and five additives, the most common reason was volatility during the evaporation procedure. The next most common reason was degradation of the substance during the heating needed for evaporation.
<P>Results and findings:<BR> From a total of 131 substances thought to be possible candidates for this approach, it was judged that 92 would be suitable under certain circumstances - most especially with polymers showing low background migration of largely oligomeric material.

<p>Find more about this project and other FSA food safety-related projects at the <a href="; target="_blank">Food Standards Agency Research webpage</a>.

Central Science Laboratory
Kings College London
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