Abstract
; Photoinitiators are widely used to cure ink on packaging materials used in food applications such as carton boards and can contaminate the food by migrating into the food. In this contribution, a fast and reliable confirmation method for the determination of photoinitiators in dry foodstuffs is described: benzophenone (BP), 4,4′‐bis(diethylamino)benzophenone (DEAB), 2‐chloro‐9H‐thioxanthen‐9‐one (CTX), 1‐chloro‐4‐ropoxy‐9H‐thioxanthen‐9‐one (CPTX), 2,2‐dimethoxy‐ 2‐phenyl acetophenone (DMPA), 4‐(dimethylamino)benzophenone (DMBP), 2‐ethylanthraquinone (EA), 2‐ethylhexyl‐4‐dimethylaminobenzoate (EDB), ethyl‐4‐dimethylaminobenzoate (EDMAB), 4‐hydroxybenzophenone (4‐HBP), 1‐hydroxycyclohexyl phenyl ketone (HCPK), 2‐hydroxy‐4‐methoxybenzophenone (HMBP), 2‐hydroxy‐4′‐(2‐hydroxyethoxy)‐2‐methylpropiophenone (HMMP), 2‐isopropyl‐9H‐thioxanthen‐9‐one (ITX), 4‐methylbenzophenone (MBP), 4,4′‐bis(dimethylamino)benzophenone (MK) and 4‐phenylbenzophenone (PBZ).

Dry foodstuffs were extracted using acetonitrile, followed by the addition of inorganic salts to precipitate fatty residues. After filtration, the extract was analysed using ultra‐performance liquid chromatography in combination with tandem mass spectrometry (UPLC‐MS/MS). Quantification was carried out using benzophenone‐d10 (BP‐d10) as internal standard. The presented method was successfully validated in‐house. Afterwards, the procedure was applied in a marketing study, investigating 97 dry foodstuffs purchased on the Belgian market. In 89% of the samples, at least one photoinitiator was detected. The photoinitiators BP, EDMA and DMPA were most frequently found, while some photoinitiators (CPTX, DEAB, DMBP, HCPK, HMBP and MK) were never detected. Copyright © 2016 John Wiley & Sons, Ltd.