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In  a surveillance study from 2008 to 2011, in total 310 food products, predominately packed in cartonboard, were collected from the German market. First, the packaging materials were analysed for their content of six photo-initiators and five amine synergists by high-performance liquid chromatography with diode array detection (HPLC-DAD). If high amounts of these substances were detected, subsequently the foodstuffs were analysed by means of HPLC-MS or tandem MS, respectively. Benzophenone (BP) was detected in 49% of the packaging materials and was thus the most often determined compound, followed by 4-methylbenzophenone (MBP, 8%), 1-hydroxy-cyclohexylphenylketone (HCHPK, 7%) and methyl-o-benzoylbenzoate (MOBB, 5%). In total, 99 foodstuffs were analysed and in 20 cases one or more photo-initiators and/or amine synergists were detected in quantities above the legally acceptable limits in food. This resulted in several notifications in the European Rapid Alert System for Food and Feed (RASFF); the best known is MBP in breakfast cereals. Contamination of the foodstuff by the photo-initiators and/or amine synergists also occurred when it was in indirect contact with the printed packaging material and no adequate barrier material was used to prevent migration. The data also clearly demonstrate that polyethylene films are not suitable to inhibit migration. Storage of samples until the best before date showed that HCHPK, BP and MBP migrate very easily via the gas phase. In contrast, 4-phenylbenzophenone and 4,4'-bis(diethylamino)benzophenone migrated only very slowly or, respectively, not in quantifiable amounts into the foodstuffs. Differences in transfer rates for HCHPK, BP and MBP from several packagings into food and Tenax(®), respectively, lead to the assumption that both the food matrix as well as the extent of cross-linking of the printing ink during curing may have an influence on the level of migration.

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Migration from recycled paperboard was monitored after 2, 4 and 9 months of storage for six test foods industrially packed in five configurations, four with internal plastic films. After 9 months, the migration of mineral oil saturated hydrocarbons into foods directly packed in the paperboard amounted to 30-52 mg/kg, which corresponded to 65%-80% of those of a volatility up to that of the n-alkane C₂₄ in the paperboard. The concentration of the migrated aromatic hydrocarbons in the foods ranged from 5.5 to 9.4 mg/kg. More than half of this migration occurred in the first 2 months. Differences between the foods amounted to mostly less than a factor of 2 and seemed to be related to porosity or permeability more than fat content. Nine photoinitiators were detected in the paperboard, of which eight migrated into the packed food at up to 24%. Several plasticisers were present in the recycled paperboard, but only butyl phthalates showed significant migration. After 9 months, up to 40% of diisobutyl phthalate and 20% of dibutyl phthalate migrated into the food with direct contact. The internal polyethylene film hardly slowed migration, but the film and the tray absorbed approximately three times more mineral oil than the food, despite constituting merely 4% of the mass of the pack. Oriented polypropylene strongly slowed migration: The highest migration of saturated hydrocarbons measured after 9 months (2.3 mg/kg) corresponded to only 3% of the content in the paperboard and included migrated polyolefin oligomeric saturated hydrocarbons. Coating of polypropylene with an acrylate further slowed the migration, but the migration from the paperboard was still detectable in four of the six samples. Polyethylene terephthalate was a tight barrier.

The case of isopropylthioxanthone (ITX) showed conclusively that the ingredients of ultraviolet printing inks may migrate into packaged foodstuffs. For multilayered materials like beverage cartons, the only way that mass transfer can occur is by the so-called set-off effect. In contrast, in the case of rigid plastics like yoghurt cups, two other methods of mass transfer, permeation and gas phase, have to be considered. In cooperation with producers of ink, plastic cups and yoghurt, a project was conducted in order to elucidate the mass transfer of ink ingredients. In addition, the influence of storage time and the age of ultraviolet lamps on the migration level was examined. The suitability of 50% ethanol as a simulant for yoghurt was also tested. ITX was chosen as a model migrant, as it is easily detectable. Furthermore, the migration of two other substances, the photo-initiator 2-methyl-4'-(methylthio)-2-morpholinopropiophenone (MTMP) and the amine synergist ethyl-4-(dimethylamino)benzoate (EDAB), which may be used in combination with ITX, was studied. Before being filled with yoghurt or 50% ethanol, the printed cups were stored under different contact conditions, with and without contact between the inner layer and the printed surfaces, in order to distinguish between the possible mass transfer ways. All analyses were performed by means of high performance liquid chromatography with diode array and fluorescence detection (HPLC-DAD/FLD). It was shown that contamination with ITX and EDAB occurs via set-off and that the degree of migration increases with lamp age and storage time of the unfilled cups. Migration of MTMP was not detectable. The results show that besides the careful selection of the appropriate raw materials for printing ink, a close monitoring of the process also plays a major role in migration control. In addition, the results proved that 50% ethanol is a suitable simulant for yoghurt.