Photoinitiators use in printed baby bibs and their migration into Tenax® by gas chromatography–mass spectrometry

A simple and accessible gas chromatography–mass spectrometry method was developed to determine photoinitiators (PIs) in plastics for food contact and their migration into Tenax®. The method showed analytical performance suitable for compliance assessment. The limit of detection values found were as follows: for benzophenone and 4-(4-morpholinyl)benzaldehyde ~3 μg kg−1 food (6 dm2 kg−1 food), for 4-methylbenzophenone and ethyl-4-(dimethylamino)-benzoate ~1.5 μg kg−1 food and for 2-ethylhexyl 4-(dimethylamino)benzoate ~43 μg kg−1 food. For all the other PIs studied, limits of detection lower than 1 μg kg−1 food were found. The method was applied to analyse samples of plastic baby bibs collected in European market. Results indicate that several unauthorised PIs are in use to print bibs. The most commonly detected PIs were benzophenone detected in nearly all samples and isopropylthioxanthone quantified in 12 out of 22 samples. Several non-evaluated PIs were detected: triphenyl phosphate, 2-ethylanthraquinone, 2,2-dimethoxy-2-phenylacetophenone, 4-(4-methylphenyltio)benzophenone, 1-hydroxycyclohexyl phenyl ketone and 4,4′-bis(diethylamino)-benzophenone. These two latter PIs were found at the highest concentration (more than 100 μgg−1). Testing a selection of samples for migration into Tenax® gave results exceeding the applicable migration limit for 1-hydroxycyclohexyl phenyl ketone with 0.532 mg kg−1 (specific migration limit = 0.01 mg kg−1) and for methyl 2-benzoylbenzoate with 0.182 mg kg−1 (specific migration limit = 0.05 mg kg−1). Although the results may be affected by a certain overestimation degree given the experimental conditions, they certainly flag an area of potential interest for surveillance and more detailed risk evaluation, particularly because bibs are often not seen by industry as food contact materials, and surveillance actions are not systematically acted.