纳米ZnO/LDPE食品包装膜及食品模拟物中ZnO含量的测定

摘要

Zinc oxide (ZnO) was determined in nano-zinc oxide food packaging and food simulants by microwave digestion with inductively coupled plasma atomic emission spectrometry (ICP-AES) and inductively coupled plasma mass spectrometry (ICP-MS).According to the European Union regulation (EU 10/2011),3％ acetic acid was chosen and ultrapure water was used as food simulants,the test was carried out at 40 ℃ for 10 days.The amount of ZnO in food simulant was analyzed by ICP-AES and ICP-MS.The results showed the calibration curve of Zn was linear in the range of 0.1-5 mg/L with correlation coefficients no less than 0.9998.The spiked recoveries at three spiked levels were in the range of 91.2％-110.2％ with relative standard deviations (RSD) of 0.3％-6.8％.The limit of detection (LOD) was 0.015 mg/L,0.03 mg/L and 0.03 μg/L respectively;the limit of quantitation (LOQ) was 0.05 mg/L,0.1 mg/L and 0.1 μg/L respectively.This method was precise,highly sensitive and accurate.This method was applied in determination of nano ZnO amount in three types of film and result was (4.71 ±0.19) g/kg,(9.20-±0.49) g/kg and 12.87 ±0.33 g/kg respectively.The amount of nano ZnO in 3％ acetic acid food simulates at 40 ℃ for 10 days was (2.35 ±0.02) mg/kg,(3.54 ±0.01) mg/kg and (4.12 ±0.35) mg/kg respectively;the amount of nano ZnO in ultrapure water simulate at 40 ℃ for 10 days was (24.65 ±0.68) μg/kg,2(4.80 ± 1.25)μg/kg and (45.85 ±0.32) μg/kg,respectively.%建立了微波消解/电感耦合等离子体原子发射光谱(inductively coupled plasma atomic emission spectrometer,ICP-AES)及电感耦合等离子质谱仪(inductively coupled plasma mass spectrometer,ICP-MS)对纳米氧化锌/低密度聚乙烯(纳米ZnO/LDPE)薄膜及食品模拟物中ZnO含量的检测方法.根据EU10/2011选择30 g/L乙酸及超纯水为食品模拟物,将纳米ZnO/LDPE薄膜在40℃下浸泡10 d,测定食品模拟物中的ZnO含量.结果表明:Zn在0.03 ～ 100μg/L及0.1～5 mg/L的浓度范围内线性关系良好,相关系数不低于0.999 8,在低、中、高3个水平进行加标实验,加标回收率在91.2％ ～ 110.2％之间,相对标准偏差(RSD,n=6)为0.3％ ～ 6.8％,方法在消解液、30 g/L乙酸及超纯水的检出限(LOD)分别为0.015 mg/L,0.03 mg/L及0.03 μg/L,方法的定量限(LOQ)分别为0.05 mg/L,0.1 mg/L及0.1μg/L,方法精密度好,灵敏度高,定性定量准确.采用该方法测得,实验室3种自制纳米复合薄膜中ZnO含量分别为(4.71±0.19),(9.20±0.49)及(12.87±0.33) g/kg,在40℃10 d后,3％乙酸(w/v)食品模拟物中ZnO的含量分别为(2.35±0.02),(3.54±0.01)及(4.12 ±0.35) mg/kg,在水食品模拟物中ZnO的含量分别为(24.65±0.68),(24.80±1.25)及(45.85 ±0.32)γg/kg.