Determination Of Photoinitiator Irgacure 907 And Investigation Of Its Penetration Behavior In Food Plastic Packaging Based On Surface-enhanced Raman Spectroscopy

Photoinitiators are one of the key components of UV-cured inks,which can directly affect the speed and degree of curing,they are widely used in the printing industry of food packages.However,residual photoinitiators from the ink on the package surface can easily migrate into food,resulting in potential harm to human health.At present,conventional methods for the detection of photoinitiators are mainly chromatography techniques and chromatography coupled with mass spectrometry methods.However,these traditional methods are time-consuming and complex of sample pre-treatment.Therefore,the rapid detection technology of photoinitiators is of great significance for ensuring food safety.In addition,studying the penetration behavior of pollutants in packaging materials is the key to evaluating the barrier property of packaging materials,but there is a lack of intuitive and effective research methods currently.In this paper,an analytical method for surface-enhanced Raman spectroscopy(SERS)was established to detect the residue of photoinitiator 2-Methyl-4’-(methylthio)-2-morpholinopropiophenone(Irgacure 907)on food plastic packaging and investigate the penetration behavior of Irgacure 907 in different plastics.The main research contents and results are as follows:(1)The feasibility of SERS method detection of seven photoinitiators:Diphenyl-(2,4,6-trimethylbenzoyl)phosphine oxide(TPO),2-Isopropylthioxanthone(ITX),2-Ethylhexyl-4-dimethylamino benzoate(EHA),4,4’-Bis(dimethylamino)benzophenone(MK),4-Chlorobenzophenone(CBP),Ethyl-4-(dimethylamino)benzoate(EDB),and Irgacure 907was evaluated firstly.The result showed that Irgacure 907 was more suitable for the detection by SERS technology based on gold nanoparticles.(2)In situ SERS determined the residue of Irgacure 907 on the surface of three types of food plastic packaging:polyethylene(PE),polypropylene(PP)and polyethylene terephthalate(PET).Irgacure 907 had a good linear relationship in the concentration range of 0-10 mg/L.The partial least square(PLS)model of Irgacure 907 on PE with a correlation coefficient at 0.9900 and root mean square error of calibration of 0.516.The limit of detection(LOD)of Irgacure 907 on PE was 0.41μg/dm~2.Moreover,the PLS model of Irgacure 907 on PP with a correlation coefficient at 0.9851 and root mean square error of calibration of 0.629.The LOD of Irgacure 907 on PP was 0.53μg/dm~2.Furthermore,the PLS model of Irgacure 907 on PET with a correlation coefficient at 0.9816 and root mean square error of calibration of 0.698.The LOD of Irgacure 907 on PET was 0.33μg/dm~2.The established SERS method was simple,rapid and high sensitivity,which was suitable for the determination of residue of Irgacure 907 on food plastic packaging.(3)The penetration behavior of Irgacure 907(200 mg/L)in plastics was monitored by the established SERS method.The influence of common solvents(acetone,acetonitrile,methanol,ethyl acetate and xylene)and different plastic materials(PE,PP and PET)on the penetration of Irgacure 907 was studied.The results showed that Irgacure 907 could penetrate through PE(thickness 80μm)after 3 h exposure,but only penetrated into 40μm of PP(thickness 80μm)and PET(thickness 80μm)after 20 d exposure when acetone,acetonitrile and methanol were used as solvents.Irgacure 907 in ethyl acetate penetrated through PE when exposed for 6 h,and penetrated into 40μm of PP and PET when exposed for 20 d.In addition,Irgacure 907 in xylene penetrated through PE after 12 h exposure,but only penetrated into 40μm of PP and 20μm of PET after 20 d exposure.Comparing the penetration rate of Irgacure 907 and the peak intensity of Irgacure 907 at different depths under the same exposure time,the order of permeability of Irgacure 907 in different solvents on plastics was acetone>acetonitrile>methanol>ethyl acetate>xylene.The ability of PET and PP to block the penetration of Irgacure 907 was stronger than that of PE.