Identification of potential migrants from epoxy and organosol coatings used in metal food cans

Abstract

The coatings of metal cans may release complex mixtures of migrants into the contained foods, including non-intentionally added substances (NIAS), such as reaction products. All migrating substances should be studied to demonstrate their safety. In this work, the characterisation of two epoxy and organosol coatings was performed using several techniques. Firstly, the type of coating was identified using FTIR-ATR. Screening techniques based on purge and trap (P&T) and solid-phase microextraction (SPME) coupled to GC-MS were used to investigate volatiles from coatings. For the identification of semi-volatile compounds, an appropriate extraction was performed before analysis by GC-MS. The most abundant substances were compounds with at least one benzene ring and an aldehyde or alcohol group in their structures. Furthermore, a method to quantify some of the identified volatiles was explored. Secondly, HPLC with fluorescence detection (HPLC-FLD) was used to determine non-volatile compounds such as bisphenol analogues and bisphenol A diglycidyl ethers (BADGEs), with subsequent confirmation by LC-MS/MS. Additionally, migration assays were performed by this technique to determine non-volatile compounds migrating into food simulants. Bisphenol A (BPA) and all BADGE derivatives except BADGE.HCl were detected in the migration extracts. Moreover, BADGE-solvent complexes such as BADGE.H₂O.BuEtOH, BADGE.2BuEtOH, etc. were also tentatively identified using the accurate mass provided by time-of-flight mass spectrometry (TOF-MS).

Keywords:

• Screening
• P&T-GC-MS
• SPME-GC-MS
• LC-MS
• coatings
• BADGE
• BPA

Acknowledgments

Authors are grateful to “Ministerio de Ciencia, Innovación y Universidades” for the Predoctoral fellowship (ref. PRE2019-088195) awarded to Patricia Vázquez Loureiro. Authors like to thank the use of RIAIDT-USC analytical facilities.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This research was funded by the Ministerio de Ciencia, Innovación y Universidades, by Fondo Europeo de Desarrollo Regional (FEDER), and by Agencia Estatal de Investigación Ref. No. PGC2018-094518-B-I00 “MIGRACOATING” (MICIU/FEDER, UE).