Migration of chemicals in the hottest plastic pack

The migration of chemicals in plastic packaging materials

Abstract: food safety has become the focus of global attention, and food packaging safety is an important part of food safety. In this paper, the residual chemical substances and analytical progress in food plastic packaging materials in recent years are reviewed

key words: migration, food packaging, food pollution, food safety, chemical components

when polymer packaging is manufactured, some chemical additives or additives are often added to improve its performance. These additives or additives, together with polymer monomers, oligomers, copolymers, macromolecular degradation products, etc., will migrate into food during the contact between polymer packaging and food, resulting in potential harm to human health. How much chemical substances remain and dissolve when plastic packaging materials are in contact with food in the medium and long term of use has always been a suspense for people, and it is also a subject faced and studied by analysts. In recent years, with the development of analytical technology, especially the online application of HPIC, GC and MS, the residual and dissolved chemicals have been gradually revealed. This paper summarizes the research progress in this area

1. Polyethylene (PE) products

as the residue of chemicals in packaging materials, the research mainly includes material test and dissolution test. There are many extraction methods of samples, such as Soxhlet extraction, reflux extraction, room temperature leaching extraction, ultrasonic extraction and supercritical extraction, but the simplest methods are room temperature leaching and ultrasonic extraction. Because the components in plastic products are extremely complex, in addition to the main raw materials or monomers, plasticizers, antioxidants, UV absorbers, lubricants and other components are also added in the production process, and are subject to high temperature and high pressure treatment. Therefore, the most effective methods to analyze these components are HPLC, GC and MS Hecun et al. Discussed the analytical method of simultaneous determination of 28 antioxidants and ultraviolet absorbers by HPLC with cyclohexane-2-propanol (1+1) mixed solvent soaked overnight at 37 ℃, TSK gel ods-80 TS column and acetonitrile Monowater (6+4) as mobile phase. The method is very simple, with a recovery rate of 86.8% - 127.0%, and a lower limit of quantification of 2.0-g · kg-1. It is used for the residue investigation of chemical substances in plastic bags, fruit bags, condiment bags and fresh-keeping bags of PE materials and their molded products on the market. The determination results showed that additives were detected in most material samples, and the residue was 50-1000mg · kg-1. Among them, the highest gunshot rate is gongrganox 1076, followed by Irgafos168, ganox 1010, tinuvin 120, naugard xi= I, etc. The detection rate of n-heptane soaking solution is the highest for molded products. Irgafos168 (content 0..73mg · L-1) is detected in 4 of 8 samples, Irganox 1076 (content 0.24~2.11mg · L-1) is detected in 3 samples, and BHT (0.57mg · L-1) is detected in 1 sample. The structure of these substances is confirmed as:

because the above method is only limited to substances with absorption in the UV region, it cannot detect substances without absorption. Later, in order to broaden the scope of analysis and obtain more information. Hecun et al. Also discussed the GC-MS method and combined it with HPLC method. The GC column is db-1 (5m long, 0.25 inner diameter μ m. Film thickness 0 l μ m) , temperature programmed (50 ℃ → 20 ℃/min → 300 ℃) method for simultaneous determination of 53 plastic additives. Among them, there are 16 kinds of antioxidants: phenols, 2 kinds of phosphoric acids, 3 kinds of sulfur-containing compounds; 9 kinds of UV absorbers; Lubricants: 5 kinds of fatty amines, 4 kinds of fatty acids, 4 kinds of fatty acid vinegar, 7 kinds of aliphatic carbohydrates; There are 3 kinds of plasticizers. The method investigated 52 commercial PE packaging materials. The determination results showed that the detection rate and residue of samples were: antioxidant: bht28.8% (50-460mg · kg-1), Irganox 1076 48,0% (100-1460mg · kg-1), Irgafos 16830 8% (200-1010mg · kg-1); Lubricant: oleamide 44 2% (270-2000mg · kg-1), steamide 36 5% (34. 840mg · kg-1), erucamide 21.1% (590 - 1290mg · kg - `), palmitamide 7 7% (110-130mg · kg - `), behenamide 3, 8 EO (200mg · kg-1); Plasticizers: di-t phthalate vinegar (DBP) 15.3o% (mg "kg-1), di-octyl phthalate (DOP) 11.5% (50--230mg · kg-), t-benzoate vinegar (BBP) 5.8% (14. 180mg · kg`) and silicon compounds

2, polystyrene (PS) products

Sugita and others have used headspace GC to determine the residual benzene (to), ethyl benzene (EB), cumene (IPB), n-propylbenzene (PB) and styrene (st) in PS containers Analysis methods of five volatile substances, for residual st oligomers, Hecun et al. ". ·] used the literature Yichuan method to make the following lessons about its chemical structure

the author used this method to investigate 25 samples such as cups, lunch boxes, instant noodles, etc. The results showed that all st polymers and trimers were detected, and their concentrations were 90-1030mg · kg-1 and 650-20770mg · kg-1, respectively. Among them, 1-phenyl-4- (1 ` -phenylethyl) Tetralin accounted for about 2/301 of the total detected. 5.2~62.4mg · kg-1st trimer-a was also detected in containers for ramen, cut noodles, buckwheat, Shaomai and noodles. At the same time, the dissolution amount is related to the polarity of solvent and the type of PS. the higher the fat solubility is, the greater the dissolution amount is; High pressure polystyrene (HIPS) expanded polystyrene (EPS) ordinary polystyrene (GPPS)

at present, although there is no sufficient reason to prove that st dimers and trimers have hormone like effects, they have been regarded as endocrine disrupting chemicals. Therefore, it is still a matter of concern

3. Polyvinyl chloride (PVC) products

Hecun and others developed an analytical method for the simultaneous determination of 89 additives in PVC products on the basis of literature. Among them There are 21 antioxidants, 22 lubricants, 34 plasticizers, 9 ultraviolet absorbers and 3 others. This method is used for the investigation of additive residues in PVC films, containers, bags, toys, packages and polyvinylidene chloride films for casings. The results showed that in addition to the high concentration of nonylphenol (530-5500mg · kg-1), lubricants, plasticizers, UV absorbers and other components were also detected. The standard recoveries of 50 antioxidants, UV absorbers and lubricants are 53.2% - 118.0%; The recoveries of 39 plasticizers were 69.3% - 119.5% The lower limit of quantification of GC-MS is 50-500mg · kg-1. In addition, pianshu et al. Used n-heptane as soaking solvent, investigated adipic acid vinegar compounds in 49 PVC plastic bags containing meat, fish shellfish, vegetables and grains by GC-MS. Results di-n-hexyladipate (dnhexa) was detected in 47 samples Di-n-heptyladipate (dnha), di-n-octylalipate (dnoa), di-n-decyladipat e (dnda), di-2 -ethyl ibexyladipate (DEHA) and an unknown peak aafx, 1 the average value of the substance is 7000mg · kg-1

4、 Polycarbonate vinegar (PC) products

bisphenol A (BPA) is a newly discovered "endocrine disrupting chemicals (ECD)" in recent years. It was first discovered by krishnann and others in the test of spa detected from PC experimental containers on the proliferation of human breast cancer cell line (MCF-7). This has attracted extensive attention to food packaging materials all over the world. Sugita and others studied the use of tskgel ods-80 TS column (inner diameter 4.6mm, length 250mm, particle size 51 μ m) , mobile phase with water and acetonitrile as gradient HPLC method for the determination of BPA in PC products. And 5~80mg · l-1bpa was detected from the samples of milk bottles, milk cups, infant tableware, bowls and so on. Japanese standard is 2 5mg · L-1, exceeding the standard times, and the substances dissolved at the same time are also diphenylca bond (DPC), pH, 4-tert-butyl phenol (BTP. Many people don't understand why to do the change experiment? First, let's talk about the experimental principle h), 4- (1, 1, 3, 3-tetramethylbutyl) phenol (TMBP), whose detection concentration is in the range of tens to hundreds of Mg · L-1. For the residues and detection methods of BPA in food and its packaging materials, see the literature

5. There are few reports on the research of residues and dissolved chemicals in melamine resin (MF) molded products

MF molded products. However, the problem of formaldehyde dissolution is often concerned by countries. A very simple method for determining the content of formaldehyde is reported in the literature, that is, in the 0.02mol · l--1] acetate medium with pH 5.0, the reaction product of formaldehyde and hydrazine sulfate has a sensitive adsorption reduction wave at the potential of - 1.04v, so it takes only 3 minutes to determine it by Oscillopolarography. This method was used to investigate 25 samples of MF water cups, rice bowls, plates and dishes sold in the market. The determination results showed that formaldehyde was detected in all samples, and most of them exceeded the national standard of ≤ 30mg · L-1. Some samples detected formaldehyde concentration as high as 1219mg · L-1, which exceeded the standard by 40.6 times. It can be seen that the sanitary supervision and testing of MF molded products can not be ignored

6. Summary

the "white pollution" caused by plastic products to the environment is well known. However, the research on the residual and dissolved chemicals in plastic products has only begun in recent years. Because there are many kinds of plastics, the composition of additives is also quite complex. Recently, not only many unknown ingredients have yet to be identified, but also the toxicological effects of many known ingredients have not been clarified. Therefore, many departments of raw materials industry and equipment industry of the Ministry of research, industry and information technology jointly organized the first working meeting of the upstream and downstream cooperation mechanism of civil aircraft aluminum in Shanghai, and the research work is waiting for 98.07. China is already a large country of plastic production and use, and there is a lack of research reports in this area at present. European and American developed countries have targeted regulations on the use of food contact materials and appliances. FDA stipulates that when the cumulative dietary concentration of a food contact substance (including food packaging materials and appliances) is less than 0.5ppb, FDA believes that it is safe for human body. When the cumulative dietary concentration is greater than 1ppm, it must be subject to the restrictions of FDA regulations like food additives before entering the U.S. market UJ. EU has made general requirements for food contact materials in 89/109/EEC: 1) all food contact materials and appliances must be produced and processed according to GMP; 2) Labeling system must be implemented for all food contact materials and appliances; The experimental results can be queried and printed (force displacement 3) the provisions of some special instructions J. The 90/128/EEC and its amendments stipulate the materials approved for use in food contact within the EU. There is still a lot of meaningful work to be done on the research of component migration of food polymer packaging materials

source: Huang Duyu, School of light industry and food engineering, Guangxi University