Non-targeted screening for contaminants in paper and board food-contact materials using effect-directed analysis and accurate mass spectrometry

ABSTRACT

Due to large knowledge gaps in chemical composition and toxicological data for substances involved, paper and board food-contact materials (P&B FCM) have been emerging as a FCM type of particular concern for consumer safety. This study describes the development of a step-by-step strategy, including extraction, high-performance liquid chromatography (HPLC) fractionation, tentative identification of relevant substances and in vitro testing of selected tentatively identified substances. As a case study, we used two fractions from a recycled pizza box sample which exhibited aryl hydrocarbon receptor (AhR) activity. These fractions were analysed by gas chromatography (GC) and ultra-HPLC (UHPLC) coupled to quadrupole time-of-flight mass spectrometers (QTOF MS) in order tentatively to identify substances. The elemental composition was determined for peaks above a threshold, and compared with entries in a commercial mass spectral library for GC-MS (GC-EI-QTOF MS) analysis and an in-house built library of accurate masses for substances known to be used in P&B packaging for UHPLC-QTOF analysis. Of 75 tentatively identified substances, 15 were initially selected for further testing in vitro; however, only seven were commercially available and subsequently tested in vitro and quantified. Of these seven, the identities of three pigments found in printing inks were confirmed by UHPLC tandem mass spectrometry (QqQ MS/MS). Two pigments had entries in the database, meaning that a material relevant accurate mass database can provide a fast tentative identification. Pure standards of the seven tentatively identified substances were tested in vitro but could not explain a significant proportion of the AhR-response in the extract. Targeted analyses of dioxins and PCBs, both well-known AhR agonists, was performed. However, the dioxins could explain approximately 3% of the activity observed in the pizza box extract indicating that some very AhR active substance(s) still remain to be identified in recycled low quality P&B.

KEYWORDS:

• Food packaging
• non-target analysis
• high-resolution mass spectrometry
• paper and board
• effect-directed analysis
• aryl hydrocarbon receptor activity

Acknowledgements

The authors thank Non-linear Dynamics for supplying the Prognenesis Qi software. Also, thanks to Michael Dickinson and Antony Lloyd, FERA Science Ltd, York, UK; Kristine Grønning Kongsbak, The Molecular Toxicology Research Group, National Food Institute, Technical University of Denmark, Copenhagen, Denmark; as well as the laboratory technicians at the National Food Institute, Technical University of Denmark, Copenhagen, Denmark. Also Annie Foverskov, Birgitte Møller Plesning and laboratory technician student Christine Blak Krøll Nielsen for their contribution to this paper. Anni Helleskov and Tommy Licht Cederberg performed the analyses for dioxins and non-ortho-PCBs.

Disclosure statement

No potential conflict of interest was reported by the authors.

Supplementary material

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Additional information

Funding

The authors acknowledge the Danish Government Food Settlement II for supporting the grant used to conduct the work.