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To develop LC-MS methods using atmospheric pressure ionisation techniques (LC-APcI-MS) for the determination of a suite of 'difficult' compounds at low detection levels. These methods were then modified to encompass the alternative ionisation technique of electrospray ionisation (LC-ESI-MS) and a selection of methods were also extended to include tandem MS (LC-MS/MS).
<LI>To apply the methods to mixtures obtained as the total migrate or extracts from food contact paper and plastics. This would give information on the robustness of the methods in terms of potential interferences and their capability towards identifying uncharacterised, 'unknown' migrates.
The identification and measurement of non-volatile and polar substances is a relative weakness in the analytical chemist's armoury. Substances present in food packaging materials can originate from a number of sources:
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Known ingredients used to make the material, for example monomers and additives in plastics, or chemicals used in paper-making.
Known or unknown isomers, impurities and transformation products of these known ingredients.
Chemicals used to convert or fabricate the paper or plastic into its finished form; for example, inks and adhesives.
Unknown contaminants, especially those in the feedstock if paper or plastics are recycled.
These substances may be important for consumer safety and improved methods for their analysis are needed. The development of analytical methods, for example within British Standards/Comit
de Europ
en Normalisation (BSi/CEN), has naturally concentrated on the first of these 4 sources.
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It is important to have the means to identify and quantify as wide a range of potential migrants as possible. This facility has been provided for several years now for low molecular weight substances that are volatile, by using GC-MS (gas chromatography coupled to mass spectrometry) instruments that are found in most laboratories. However, GC-MS is poor for the analysis of substances, which are non-volatile due to their high molecular weight and/or polarity. Derivatisation techniques to improve volatility for GC-MS must make some assumptions on the functional groups that the 'unknown' may contain and so can be rather hit-or-miss. Advances in LC-MS (liquid chromatography coupled to mass spectrometry) techniques have led to a rapid increase in its use for non-volatile and polar compounds, but the transfer of established LC methods to LC-MS is not always straightforward in terms of mobile phase compatibility. The consequence is that, to date, LC-MS has provided relatively little information on the polar and non-volatile substances that may migrate from paper and plastics.
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The capabilities of LC-MS methods have been explored for the analysis of polar and non-volatile substances that are present in food contact plastics, paper and coatings and may be possible chemical migrants to foodstuffs. Targeted compounds included: polyolefin additives; polyamide monomers and oligomers; polar substances: acids, glycols and diols; styrene monomer and oligomers; polyvinyl chloride additives; primary aromatic amines; inks and coatings chemicals; fluorescent whitening agents; melamine; biocides; and greaseproofing agents.
<p>Find more about this project and other FSA food safety-related projects at the <a href="http://www.food.gov.uk/science/research/" target="_blank">Food Standards Agency Research webpage</a>.