Chromatographic Verification of Photoinitiator Specific Migration Limits in Printed Barrier Packaging
Chromatographic testing via LC-MS/MS verifies photoinitiator specific migration limits in printed barrier packaging to maintain compliance.
Irgacure 907
Chemical Initiator
Rapid polymerization of printing inks under light exposure relies on photoactive compounds that generate reactive radicals when irradiated. In high speed printing of packaging materials, irgacure 907 operates as an efficient curing agent for clear and pigmented coatings. This substance initiates the crosslinking of acrylates and prevents wet ink from smearing or transferring to adjacent sheets in the stack.
Migration Risk
Unreacted photoinitiators present a significant hazard if they migrate from the printed outer surface of a carton to the food inside. Due to its low molecular weight, irgacure 907 can diffuse through the paperboard fibres during storage. This migration occurs most frequently when printed sheets are wound into rolls, causing the printed side to press directly against the unprinted food contact side.
Analytical Detection
Food safety laboratories identify residues of this substance using liquid chromatography coupled with mass spectrometry to ensure packaging complies with European and global limits. The extraction process begins by soaking a specified area of the printed board in an organic solvent. After filtration, the extract is injected into the spectrometer to measure the exact concentration of irgacure 907 against a calibrated reference standard.
If the detected concentration exceeds the specific migration limit, the batch of packaging must be rejected to prevent contamination. Modern printers often substitute this compound with larger, polymeric alternatives that cannot diffuse through the cardboard substrate.