Ion mobility quadrupole time-of-flight mass spectrometry for the identification of non-intentionally added substances in UV varnishes applied on food contact materials. A safety by design study.

Varnishes are normally applied on printed food packaging to protect it from smearing and scratching. Moreover, they may be applied on the food contact surface in order to improve resistance towards moisture and fat. Some of the compounds that make up the varnish formulation could migrate to the food. In this work, the ion mobility quadrupole time-of-flight mass spectrometry has been used to obtain drift time-aligned mass spectra in which accurate the mass of precursor ions and their fragments are used to identify both intentionally and non-intentionally added substances (NIAS). The compound 2-propenoic acid,1,1'-[2-[[3-[2,2-bis[[(1-oxo-2-propen-1-yl)oxy]methyl]butoxy]-1-oxopropoxy]methyl]-2-ethyl-1,3-propanediyl] ester was identified as a NIAS formed from the varnish monomer 2-propenoic acid, 1,1'-[2-ethyl-2-[[(1-oxo-2-propen-1-yl)oxy]methyl]-1,3-propanediyl] ester. The compound 5, 11-diethyl-7-oxo-4,6,10,12-tetraoxopentadecane-3,13-diyl diacrylate is a NIAS derived from the varnish monomer 2-propenoic acid, 1,1'-[oxybis(methyl-2,1-ethanediyl)] ester, and was found to migrate into the food simulant tested at a level of 0.03 mg kg. Finally, the NIAS, 2-{2-[2-(acryloyloxy)-1-methylethoxy]-1-methylethoxy}-1-methylethyl acrylate, an impurity of a photoinitiator used for UV curing of the varnish, was identified, and its migration of 0.14 mg kg exceeded the threshold established as safe for human consumption.