Screening methods are required to estimate consumers’ exposure to inadvertently added additives/contaminants in Food Contact Articles (FCAs) during food production. Potential migration of additives/contaminants from FCAs into food is reliably estimated if polymer identity, identity and/or concentration of additive/contaminant, and conditions of use are known. Current non-targeted methods lack either rapid or comprehensive analysis of dozens of known FCA base polymers and thousands of additives/contaminants. Therefore, we are developing a rapid, multi-polymer/contaminant/additive Direct Analysis in Real Time (DART)-HRMS screening method capable of identifying FCAs polymers and small molecules.<br/><br/>MS1 parameters on a DART-Thermo Q-Exactive were optimized on robust, documentable, and diverse polymer references (n=5) to produce diverse ions with equi-abundance. The optimized method was applied to n=124 reference materials covering &gt;75% of estimated FCA types in positive and negative modes, generating data for precise HRMS ion databases. Retail/commercial FCAs (n=152) collected between the U.S. and E.U. challenged our method and evaluated usefulness of MS1 reference polymer data. DART-HRMS polymer databases were created by common and unique ion identification using custom open-source workflows developed in KNIME with outputs/averages/merges and lists validated against theory, literature, and vendor software.<br/><br/>Reference polymer-specific ion features varied dependent on the polymer and additives present. N=124 reference polymer standards (47 structural classes) were analyzed. Unique ions (~4500) were compiled in an MS1 database. Their accuracy and utility in polymer ID was validated. Separately, a MS1 DART-additive/contaminant (n=210) database was developed from ongoing analyses. Ions within both MS1 databases were assessed for commonality and uniqueness. Polymer-specific common but non-unique ions were prioritized for MS2 analysis to assist in identifying different but related polymers. Workflows to automate polymer classification by cosine-vector matching of more unique ions and/or a-priori defined polymer structural ions are under development. Once completed, this method will provide screening data for responding to food packaging inquiries.

Identification of polymers, additives, and contaminants in food contact articles using rapid, direct - high resolution mass spectrometry

ACS Spring 2022

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