| Polyvinyl chloride (PVC) is a polymeric compound polymerized by vinyl chloride monomer. PVC film produced by adding plasticizers, antioxidants etc. and stretched has high transparency, high intensity, low temperature resistance, good self-adhesiveness and a certain permeability of oxygen and water vapor, therefore it can keep food fresh. Because the production process of PVC film has to add many plasticizers, and there will be residual antioxidants, solvents and monomer, which have a variety of hazards to human body, PVC film is unsafe to package food. Our country has limited the usage area of PVC film for food package, but because of its excellent characteristics and low cost, PVC film is still widely used in food area. At the same time, because the supervision and management are not done well, there are many kinds of food being packaged by PVC films which are made of recycled films or are not for food packaging in the markets and streets. In this paper, PVC films were identified; evaporation residue was measured; analysis methods of vinyl chloride monomer, solvents (benzene and methylbenzene), antioxidant (BPA) and plasticizers (DnOP and DBP) were established; the migration of these substances into food were studied, thereby we can find out the hazard situation of PVC film for food package and security risk of packaging some kinds of food and provide the reference basis for production supervision departments.First of all, PVC films were identified and evaporation residue was measured. Separation and purification of the PVC film sample were done by the dissolution and precipitation method using tetrahydrofuran as solvent and absolute alcohol as precipitant. The 26 film samples for food package in various kinds of areas collected from market were tested by Fourier Transform Infrared (FT-IR) spectrometry with scanning wave numbers of 4000-500cm-1 and 9 films were PVC. Evaporation residue test showed 9 PVC films'evaporation residues fit the requirement of national hygiene standard.Secondly, analysis method of vinyl chloride monomer in PVC film tested by manual-inject gas chromatography headspace (GC-HS) analysis was used. The operation condition of GC and balance condition of sample were optimized. Sample was balanced 30min at 70℃, separated by DB-WAXtre capillary column and detected by FID. VCM's linear range was 0-4.977μg and R2 was 0.9994. Detection limit was 0.199mg/kg. The recoveries were 91.04%-103.27%and RSD(n=3) were 3.76%-4.50%. This method can meet the analysis of residual VCM in PVC film. VCM were not found in the 9 PVC film samples. To a certain degree, the results showed that the situation of residual VCM in PVC film was not serious.Analysis method of residual benzene and methylbenzene in PVC film and food (apple, fried bread stick/fried dumpling, beer) tested by gas chromatography (GC) was used. Sample was separated by HP-5 capillary column and detected by FID. Benzene's linear range was 0.88-88.00μg/mL and methylbenzene's linear range was 0.866-86.600μg/mL with good linear relations and R2 were 0.9995 and 0.9992. Detection limit were 0.220μg/mL and 0.216μg/mL. The recoveries were 69.88%-87.55%and RSD(n=3) were 1.86%-4.98%. This method can meet the analysis of residual benzene and methylbenzene in PVC film, apple, fried bread stick/fried dumpling and beer. Residual benzene and methylbenzene in 9 PVC film samples and their migration into food were tested. The results showed that benzene was found in 3 PVC films, methylbenzene was found in 5 PVC films, benzene and methylbenzene were both found in 2 PVC films and residual quantities were much lower than the methylbenzene level of EU. The migration test showed that benzene and methylbenzene were not found in the food without being packaged by the films in which benzene and methylbenzene were found. Benzene and methylbenzene were not found in beer. In the food packaged by corresponding PVC films in which benzene and methylbenzene were found, both were not found in apple; benzene and methylbenzene's migration quantities into fried bread stick /fried dumpling had relation with their residual quantities in PVC film, package time and might have relation with production process and structure such as gap size of film. Methylbenzene's migration quantities 0.880-1.168mg/kg into fried bread stick/fried dumpling were in the range ruled by EU, but benzene's migration quantities 0.883-1.024mg/kg were much higher than the index of EU.Analysis method of BPA in PVC film and food (apple, fried bread stick/fried dumpling, beer) tested by high performance liquid chromatography (HPLC) was used. BPA s linear ranges were 0.0001-0.5mg/mL and 0.0001-0.05mg/mL with good linear relations and R2 were 0.9990 and 0.9999. Several extraction methods were optimized. PVC film was extracted 30min by ultrasonic in V(dichloromethane):V(methanol)=9:1; apple, fried bread stick/fried dumpling, beer were extracted 1h by ultrasonic corresponding in V(dichloromethane):V(methanol)=7:3, V(dichloromethane):V(methanol) =9:1 and V(dichloromethane):V(methanol)=6:4. The recoveries were 85.15%-100.02%. RSD(n=3) were 1.17%-4.72%. Detection limits of PVC film, apple, fried bread stick/fried dumpling and beer were 0.01mg/kg,0.02mg/kg,0.02mg/kg and 0.01mg/L. BPA in 9 PVC film samples and its migration into food were tested. The results showed that BPA was found in 4 PVC films with the contents of 20.823-49.125mg/kg. The migration test showed BPA was not found in the food without being packaged by the films in which BPA was found. In the food packaged by corresponding PVC films in which BPA was found, BPA was found 0.403mg/kg in apple packaged for 4 months. BPA was found 0.109mg/kg and 0.079mg/kg in fried bread stick and fried dumpling packaged for 60min. The migration quantities into the food packaged by PVC film had relation with BPA content in PVC film, package time and temperature. The migration quantities were safe relatively.Analysis method of DnOP and DBP in PVC film and food (apple, fried bread stick/fried dumpling, beer) tested by SPE-HPLC was consummated and innovated. DnOP's linear range was 9.8×10-6-0.0098mg/mL and DBP's linear range was 5.235×10-6-0.01047mg/mL with good linear relations and R2 were 0.9994 and 0.9997. Several extraction and clean-up methods were optimized. The clean-up method combined of acticarbon column(columnl) and florisil column(column2) was better than the single column methods. DnOP and DBP detection limits in film extract and apple extract were 8.3-10 times those cleaned up by the two columns. PVC film was extracted 30min by ultrasonic in hexane; apple, fried bread stick/fried dumpling, beer were extracted 1h by ultrasonic corresponding in V(acetone):V(hexane)=1:3, V(acetone):V(hexane)=1:3 and V(acetone): V(hexane)=1:4. Extract flew past columnl. Columnl was washed by 5mL dichloromethane. The eluentl flew past column2. Column2 was washed by 5mL V(acetone):V(hexane)=1:4. The recoveries of DnOP and DBP were 82.24%-105.39%. RSD(n=5) were 1.08%-9.67%. Detection limits were 0.00465-0.02616mg/kg. This method can meet the analysis of DnOP and DBP in PVC film, apple, fried bread stick/fried dumpling and beer. DnOP and DBP in 9 PVC film samples and their migration into food were tested. The results showed that DnOP was found in 6 PVC films, DBP was found in 5 PVC films, DnOP and DBP were both found in 3 PVC films, only 4 PVC films met requirement of EU. The migration test showed that DnOP/DBP were not found in the food without being packaged by the films in which DnOP/DBP was found. In the food packaged by corresponding PVC films in which DnOP/DBP was found, DnOP was found highest 0.3230mg/kg in apple packaged for four months. DnOP was found highest 0.3852mg/kg in fried bread stick and fried dumpling packaged for 60min. The migration quantities into the food packaged by PVC film in which DnOP/DBP was found had relation with DnOP and DBP content in PVC film, packaging time and temperature and might have relation with the production process of film and the character of food. The highest migration of DBP 0.3383mg/kg in fried bread stick exceeded the index 0.3mg/kg of EU. According to BPA's TDI 0.01mg/kg(weight)·d, DnOP's TDI 0.01mg/kg(weight)·d and DBP's TDI 0.01mg/kg(weight)·d, the result showed the food had little risk.In addition, the results of dissolution of BPA and DnOP into food simulants showed that the quantity of BPA and DnOP transferred to simulants increased by the dipped time and had relation with what the food simulant was. The BPA highest dissolutions in hexane,4%acetate acid,20%ethanol and water were 20.0044mg/kg,4.9210mg/kg, 0.7512mg/kg and 0.6714mg/kg; the DnOP highest dissolution was 51.9358mg/kg in hexane and the DnOP highest dissolutions in edible oil, 4%acetate acid,20%ethanol,10%salt were 41.2482mg/kg,9.0854mg/kg, 6.6990mg/kg and 6.4748mg/kg and the DnOP highest dissolution in water was 2.1340mg/kg. BPA and DnOP were quite easy to migrate from PVC films into fatty food, while some PVC films packaging pickled food, alcoholic beverages and acid food might have great risk too. Customers had better not use PVC film to package fatty food especially the food with high temperature or had better eat the food as quickly as possible. |
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