Determination And Migration Of Photoinitiators In Paper And Board Food Packaging Materials

Paper base package materials have become main food packaging materials for food packaging industries, because they have extraordinary physical, mechanical and environmental properties. The analysis of contaminations and the theory of migration are highlighted. Ultraviolet (UV) inks are widely used in food packaging materials because of its excellent properties. Photoinitiators (PIs) are poisonous and irritate the skin, and they are also easy to volatilize and migrate.In this paper, a novel, single step analytical method was established by using gas chromatography-mass spectrometry (GC/MS) for detecting a series of PIs, which were Benzophenone (BP),4-Methylbenzophenone (MBP),1-Hydroxycyclohexyl phenyl ketone (Irgacure184),2-Isopropylthioxanthone (ITX), Ethyl-4-dimethylaminobenzoate (EDAB) and2-Ethylhexyl4-dimethylaminobenzoate (EHDAB). Extraction is carried out with ethyl acetate by ultrasonic solvent extraction. The comparison of extraction methods of PIs between ultrasonic and Soxhlet showed that there was no significant difference between their efficiency of the extraction, but ultrasonic solvent extraction cost less time. Therefore, ultrasonic solvent extraction method was used over the experimental process. Samples were analyzed by gas chromatography-mass spectrometry operated in selected ion monitoring (SIM) mode. Under final conditions, The six PIs have good linear relations (R2>0.9989) in the rang of10～200μg/L. The method detection limits and method quantification limits of all PIs were0.3～2.6μg/kg and1～8μg/kg, respectively. The recovery of6PIs at the3concentrations researched (0.30μg/kg、0.60μg/kg、1.0μg/kg) was ranging from66.7%-89.4%, with the Relative Standard Deviation (RSD) of4.2～10.6%(n=6).Partition coefficients (Kpaper/air) of six kinds of PIs in cartonboard and kraft were determined by microsampling. The result showed Kpaper/air values decreased with an increasing temperature, Kpaper/air values of100℃were lower than Kpaper/air values of100℃. It indicated that the comtaminants in paper and board packaging materials were more dangerous to food at high temperature. Kpaper/air had a proportional relationship with the grammage and the thickness of paper sample. The lower of the grammage and the thickness, the lower of Kpaper/air value would be. Kpaper/air of EDHAB was the lowest of six PIs, and Kpaper/air of MBP was the highest.Desorption kinetics and transfer phenomena of PIs between package materials and soybean flour were also studied. Temperature had effect on the migration of the PIs. In the range of temperature studied (70℃and100℃), migration rate was increased with an increasing temperature, whereas desorbing equilibrium time was decreased with an elevating temperature. The migration rate of PIs of cartonboard were higher than the migration rate of kraft. The lower the grammage and thickness, the higher of the migration rate and the easier to reach desorbing equilibrium. The migration rate of BP and Irgacure184were higher among six PIs. The migration rate was higer while the boiling point of PIs was lower. The migration rate of PIs were highest while fat content of soybean flour was19.64%. Soybean flour of more fat content prosessed greater adsorption capacity and the migration rate of PIs were higher.