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Methods and Searchable Spectroscopic Libraries to Identify Substances Migrating above a One Part Per Billion (109) Threshold


The experimental work was preceded by a literature review of the threshold of regulation concept and mass spectrometric methods for part-per-billion measurements and identification of substances migrating from food contact materials. This review was used to guide the selection and refinement of analytical methods. Four MS-based analytical techniques were then investigated.
Headspace gas chromatography mass spectrometry (HS-GC-MS) for the analysis of volatile substances.
Liquid injection gas chromatography mass spectrometry (GC-MS) for the analysis of semi-volatile substances either directly in a food simulant or in a solvent extract.
Liquid chromatography mass spectrometry (LC-MS) for the analysis of non-volatile substances.
Inductively coupled plasma mass spectrometry (ICP-MS) for the analysis of inorganic/metallic elements.
These techniques were first used to analyse mixtures of standard substances, to determine their sensitivity towards representative chemicals that may migrate from packaging materials. Analysis was then performed in the presence of crude solvent extracts of paper and plastics packaging materials, to see if the presence of co-extractives impaired the performance of the methods. Finally, the methods were used to collect spectra of typical plastics extractives, to assist in any future assessment of migrates from plastics intended for food contact.

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The threshold of regulation (ToR) approach is under consideration in Europe as a means to limit the amount of migration testing and toxicological testing needed in the area of migration from food contact materials. It is based on the premise that there could be an exposure level below which substances pose negligible health risk to consumers. Therefore, substances migrating below this level may not need to be specifically permitted for use. The ToR approach has been proposed as a way to deal with otherwise seemingly intractable issues, such as contaminants potentially present at very low levels in recycled materials, secondary packaging and ink components.
One scientific and technical problem is that the approach has little practical value if there are no analytical methods capable of detecting and identifying unknown substances at the ToR level required by toxicologists. A 1 ppb migration threshold has been proposed.
In this project we evaluated a suite of four complementary mass spectrometry (MS)-based analytical approaches for their capabilities at the 1 ppb ToR level. The objectives of the project were:

To establish the capabilities of advanced analytical techniques for detecting and identifying unknown substances down to the level of 1 ppb; and
To create polymer-specific libraries of EU-listed plastics ingredients and non-listed (but still permitted) impurities so that decisions could be made on which substances detected above any ToR are 'permitted' and which are not.
<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
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