Abstract: Microwave digestion followed by inductively coupled plasma mass spectrometry (ICP-MS) was used to detect the migration of copper from a laboratory-made nano-copper/low density polyethylene (LDPE) composite film to milk products versus the corresponding food simulants. In addition, the influence of ultraviolet (UV) radiation on the migration of copper from the composite film to milk products was evaluated as well as the influence of cooking on the migration of copper from the composite film to pure milk. The results showed that the limits of detection (LOD) and limits of quantitation (LOQ) of copper migration were 8.42 and 28.06 mg/kg, respectively. The recovery and precision expressed as relative standard deviation (RSD) of the ICP-MS method were 97.46%–107.30% and 1.98%–6.06%, respectively. The migration amount of nano-copper to yogurt was higher than that to pure milk. The migration of nano-copper from the nano-composite film with 1% copper to yogurt was significantly higher than that to pure milk under the same conditions. Moreover, the migration amount to 50% ethanol significantly decreased by 39.19–48.94 mg/kg compared with that to pure milk. The migration amounts to 3% and 4% acetic acid significantly increased by 1 598.66–1 760.92 and 1 868.97–2 159.58 mg/kg compared with that to yogurt, respectively. The migration of nano-copper to milk products did not change after UV treatment. Under cooking conditions, the migration amount was far below the regulatory limit. The existing limit does not apply to the migration amount of nano-copper to pure milk and yogurt.

Key words: nano-copper; low density polyethylene; milk products; food simulants; migration; inductively coupled plasma mass spectrometry