Novel multi-analyte method for detection of thirty photoinitiators in breakfast cereal and packaged juice

Multilayer print designs are commonly used in commercial food packaging to attract consumers. UV-curable ink is generally used in this type of printing due to its ease of application, space saving, and rapid drying; however, there have been a number of health alerts related to the contamination of food by photoinitiators in UV-curable ink. In this study, we established a multi-analyte method by which to detect 30 photoinitiators simultaneously. We then applied this method to the analysis of five breakfast cereals and ten types of packaged juice to detect the presence of photoinitiator contamination. Sample treatment was performed using the QuEChERS (quick, easy, cheap, effective, rugged, and safe) method for the extraction of photoinitiators. Chromatographic separation of two isomers, methylbenzophenone (MBP) and isopropylthioxanthone (ITX), was achieved using a pentafluorophenyl propyl (PFP) column (1.7 µm, 100 × 2.1 mm i.d.) and MeOH: 5 mM formic acid-ammonium formate (pH 4.0) in gradient elution. The average recovery of photoinitiators from cereal was between 62.0 and 120.3%, with a coefficient of variation between 0.4 and 14.4%. The average recovery of photoinitiators from packaged juices was between 84.4 and 122.9% with a coefficient of variation between 0.5 and 9.5%. The contamination results were as follows: 13.1 ng/g triphenyl phosphate (TPP) was detected in one breakfast cereal, and 2-hydroxy-4-methoxy benzophenone (BP-3), 1-hydroxycyclohexyl phenyl-ketone (Irgacure 184), methyl-2-benzoylbenzoate (MOBB), and 2,4-diethyl-9H-thioxanthen-9-one (DETX) were detected in one of the packaged juices at levels ranging from 2.2 to 152.9 ng/g.