Comprehensive analysis of photoinitiators and primary aromatic amines in food contact materials using liquid chromatography High-Resolution Mass Spectrometry

A comprehensive strategy for the analysis of UV-ink photoinitiators and primary aromatic amines (PAAS) in food-packaging materials such as, juice tetrabricks, pouches and bags has been developed using liquid chromatography coupled to Orbitrap High-Resolution Mass Spectrometry (LC-Orbitrap-HRMS). The methodology includes both quantitative target analysis and post-run target screening analysis. The quantitative method was validated after a previous optimisation of the single-stage Orbitrap fragmentation through the Higher-Energy Collisional Dissociation (HCD) Cell. Overall, the quantitative method presented recoveries ranging from 78% to 119%, with a precision (RSD) lower than 20%, for the 18 substances in the scope of the target method. Limit of quantification (LOQ) for UV-inks photoinitiators ranged from 0.5 µg/kg^-1 for Isopropyl Thioxanthone (ITX) and 2-Ethylhexyl 4-(dimethylamino) benzoate (EHDAB) to 5 µg/kg^-1 for the rest of photoinitiators. LOQ for PAAs were 2 µg/kg^-1 except for aniline (ANL) and 3,3' dimethylbenzidine (3,3'-DMB) which was 2.5 µg/kg^-1 in the two studied simulants (acetic acid 3% and ethanol 50%). For post-run target screening a customized theoretical database, that included Bisphenols, Polyfluorinated compounds (PFCs), Phosphorus Flame Retardants (PFRs) and other substances was built. For identification purposes, a mass accuracy lower than 5 ppm, and some diagnostic ions including isotopes and/or fragments were used. The strategy was applied to 18 samples collected in the Valencian region (Spain). No compounds were detected when the standardised migration test was applied. However, in the destructive test, benzophenone and EHDAB were determined from tetrabrick and pouch materials. In the post-run target analysis two PFCs (Perfluorooctanoic acid and Perfluoro-1-butanesulfonate) and four PFRs (2-ethylhexyl diphenyl phosphate, tris(2-choloroisopropyl) phosphate, triphenyl phosphate and 2-ethylhexyl diphenyl phosphate) were identified.