Study On The Determination Of Nine Photoinitiators In Food Packaging Materials By Gas Chromatography-Mass Spectrometry

The printing ink of food packaging surface is one of the potential sources of food contamination.The use of traditional solvent-based inks for food packaging printing can easily lead to the residues of solvent and other volatile organic,which will bring potential harm to food safety and human health.Therefore,the UV curable ink has the merits of rapid curing rate and environmental protection,which is gradually replacing the solvent ink and widely used in paper,plastic and other food packaging field.Photoinitiator is an important component of UV curable ink,which has a direct influence on curing rates and degree.However,in recent years because of photoinitiators on the food packaging contaminated packed food incidents reported frequency.Studies have shown that the unreacted photoinitiators of the UV curing process can contaminate the food from the packing by chemical migration or physical contact,which will lead to skin contact toxicity and influence human endocrine hormones,and even lead to carcinogenicity.In view of the harm of photoinitiators,many countries have promulgated several regulations or restrictions on the use of photoinitiators in food packaging materials,the General Administration of Quality Supervision,Inspection and Quarantine of the People's Republic of China also issued the official methods of detecting the photoinitiators in food contact materials.Researchers from different countries also committed to seeking more accurate and sensitive analytical methods in order to meet the growing demands of detecting the different types of photoinitiators in food packaging.In this study,we has chosen nine representative photoinitiators based on the existing methods and the detection rates of photoinitiators,we choose nine photoinitiators as research analytes,including benzophenone,4-methyl benzophenone,4-chloro benzophenone,1-hydroxycyclohexyl phenyl ketone,ethyl 4-dimethylamino benzoate,2-ethylhexyl-4-dimethylamino benzoate,2-chlorothioxanthone,2,4-diethyl-9H-thioanthen-9-one,2-isopropylthioxanthone.We investigated the optimized sample pretreatment conditions and the detecting conditions of gas chromatography-mass spectrometry(GC-MS),and then,the proposed method was successfully applied to the simultaneous detection of the nine photoinitiators in food packaging materials.This study mainly include these aspects:In the study,we investigated pretreatment methods of real samples firstly,the ultrasonic extraction technology was applied by selecting different extraction solvents,optimizing the extraction time and temperature.And then the orthogonal design experiments were introduced in order to find the optimal experimental condition.Hence,the optimum pretreatment conditions were: all the compounds could be extracted from the food packaging materials with 15.0 m L of dichloromethane at 40? for 20 min.In our study,the GC-MS detection method has applied to detect the photoinitiators.The heating rates,carrier gas flow rate and injection temperature were optimized to get better resolution and response value of the nine photoinitiators.Finally we selected the TG-5MS capillary column as the separation column,and the flow rate was 1.2 m L/min with injection temperature of 280?.When separating the different analytes,the temperature programming could be divided into two phases: started with the initial temperature of 125 ? and heating to 175 ? with the heating rates of 8 ? / min,and then keeping 175 ? for 3 min,and then heating to 280 ? with the rate of 30 ? / min,keeping 3 min.All the photoinitiators can be separated in 15 min and obtained the satisfying resolutions.And quantified by using the selected ion monitoring mode.The limits of detection for the method were 0.7840~7.699 ?g/L(S/N=3).The recoveries of the nine photoinitiators were tested at three spiked levels and all the recoveries ranged 92.44% to 110.6% with RSD of 1.60%~9.46%(n=6).This simple,sensitive and accurate method we proposed could be applied to the determination of the photoinitiators in food packaging materials.This method could provide technical support for the quality control of the photo initiator in food packaging materials.