Simultaneous Determination of Residues of 10 Photoinitiators in Ultroviolet Curing Offset Ink for Eoo-Friendly Cigarette Labels by Gas Chromatography-Mass Spectrometry

An ink-scraping instrument with amount of ultroviolet curing offset ink controlled by ink meter was adopted for simulation of actual printing process to prepare ink samples with definite thickness. The cut sample obtained was taken and extracted ultrasonically with addition of acetonitrile and internal standard solution of deuterated anthracene for 40 min. The supernatant was extracted with mixed solution of n-hexane-ethyl acetate with volume ratio of 3：7, and purified with a purification tube containing 150 mg anhydrous MgSO₄, 50 mg C₁₈ and 50 mg N-propyl ethylene diamine. After centrifugation, the supernatant was passed through 0.45 μm filtrating membrane. The obtained filtrate was injected with split ratio of 40：1, and 10 photoinitiators were separated on DB-5MS quartz capillary column (30 m×0.25 mm, 2.5 μm) under temperature-programmed conditions, and detected by mass spectrometer. As shown by results, 10 photoinitiators could be effectively separated within 26 min, and linear ranges of the standard curves of 10 photoinitiators were 0.4-10.0 mg·L^-1, with detection limits (3s) in the range of 0.25-1.5 mg·m^-2. Test for recovery by standard addition method using actual sample as matrix was made at 3 concentration levels and results of recovery of 10 photoinitiators ranged from 89.5% to 105%, with RSDs (n=6) of the determined values not more than 7.0% . The proposed method was used for analyzing the samples prepared with blue, red, yellow and black inks, and benzophenone was detected in the samples prepared with red, yellow and black inks, with maximum detection amount of 0.39 mg·m^-2, which did not exceed the limit (20 mg·m^-2) specified in standard of YQ 69-2015.