A systematic study on the stability of UV ink photoinitiators in food simulants using GC

Abstract

AbstractSeveral studies have been published on the stability of plastic monomers and additives in food simulants. However, there are practically no published results about the stability of ink components in food simulants. In this work, the stability of two ultraviolet (UV) ink photoinitiators (PIs) in one aqueous and in two substitute fat food simulants was studied under various time–temperature conditions. Furthermore, the addition of the stabilizing agent hydroquinone monomethyl ester (HQMME) in the same conditions was considered as a comparative experiment. The PIs tested were 1‐hydroxycyclohexyl‐1‐phenyl ketone (Irgacure‐184) and benzyldimethyl ketal (Irgacure‐651). The various test conditions included exposure of 10 days to temperatures of 20, 40 and 60°C for 10% ethanol and 95% ethanol simulants, and exposure of 2 days to temperatures of 20, 40 and 60°C for isooctane. Following exposure to these conditions, the additive samples were analysed. The extracts of samples exposed to various temperature conditions as well as unexposed spiked controls and blanks were analysed by gas chromatography (GC) on a non‐polar (5%‐phenyl)‐methylpolysiloxane capillary column. The results showed that the protective effect of HQMME was not obvious in all test conditions under dark conditions. The Irgacure‐184 was quite stable under all test conditions whether the stabilizing agent was added or not. Irgacure‐651 was stable almost under all test conditions, except in 10% ethanol at 60°C. The mass spectrum of decomposed product of Irgacure‐651 was detected by GC‐MS (Mass Spectrum), and the structure of the decomposed product was obtained by mass spectrographic analysis. The method of detection and disposal is also applicable for UV ink PI migration testing from several different paper or paperboard‐plastic coating layer materials into the food simulants used in the study. Copyright © 2008 John Wiley & Sons, Ltd. 2008