Determining the trace-level photoinitiators in juices and milk from various types of packages in Taiwan by a micro-QuEChERS-based UPLC-MS/MS

The distribution of 16 photoinitiators (PIs)-benzophenone (BP) and its five derivatives, 4-methylbenzophenone (4-MBP), methyl-2-benzoylbenzoate (M2BB), 2-ethylhexyl-4-dimethylaminobenzoate (EHDAB), and the other 7 PIs-in packaged juice and milk was assessed using an UPLC-MS/MS with micro-QuEChERS. The validated method demonstrated robust linearity (≥0.9908), LOQs (juice: 0.006-7.26 ng/mL; milk: 0.004-7.14 ng/mL), intra- and inter-day accuracy (93.1%-110.1% for juice and 66.8%-114.6% for milk with relative standard deviations (RSDs) of ≤16.8%), and matrix effect with RSDs of ≤14.8%. BP exceeded the LOQ in 100% of 136 packaged juice (14.22 ± 7.60 ng/mL) and 51 milk (8.45 ± 3.25 ng/mL) samples, and the quantitation rates for M2BB and EHDAB in packaged juice were 100%. Notably, the 4-MBP in both juice and milk was significantly related to the packaging material. The method has been successfully applied to evaluate the occurrence and distribution of PIs in packaged juice and milk.