纳米铜/低密度聚乙烯复合膜在乳制品中的铜迁移

Migration of Copper from Nano-Copper/Low Density Polyethylene Composite Films to Milk Products

采用微波消解-电感耦合等离子体质谱法检测自制纳米铜/低密度聚乙烯(low density polyethylene,LDPE)复合膜中铜在乳制品中的迁移。实验对比复合膜中铜在乳制品及其对应食品模拟物中的迁移,并研究紫外照射处理复合膜后对复合膜中铜在乳制品中的迁移影响,以及蒸煮条件下铜在纯乳中的迁移量。结果表明:用微波消解-电感耦合等离子体质谱法检测纳米铜迁移量的检出限为8.42 mg/kg,定量限为28.06 mg/kg,方法的加标回收率为97.46%~107.30%,精密度为1.98%~6.06%。纳米铜在酸乳中的迁移量比在纯乳中的迁移量高,当纳米铜/LDPE复合膜中铜添加量为1%时,在相同的迁移条件下,纳米铜在酸乳中的迁移量显著高于在纯乳中的迁移量;纳米铜在50%乙醇模拟液中的迁移量显著小于纯乳,差值在39.19~48.94 mg/kg之间,在3%乙酸和4%乙酸模拟液中的迁移量显著高于酸乳,差值分别在1 598.66~1 760.92 mg/kg和1 868.97~2 159.58 mg/kg之间;紫外照射处理复合膜对复合膜中铜在乳制品中的迁移无影响;蒸煮条件下,纳米铜的迁移量也远小于法规中对金属元素迁移量的限定。现行标准中对纯乳和酸乳的食品模拟物的设定不适用于纳米铜。

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.