A method for the detection of solvent residues in black and white film packaging for liquid milk was introduced

Abstract: liquid milk is a kind of nutritional food that the public needs in daily life It is usually packed in black and white film In the process of packaging or unpacking, it occasionally smells the smell of similar paint, which is caused by the residual organic solvent in the packaging bag In this paper, gc-7800 gas chromatograph is used to test the residual solvent in the packaging bag, and the principle, parameters and test process of the equipment are described, which has certain guiding significance for the enterprises troubled by the problem of packaging odor Key words: dairy products, liquid milk, black and white film, solvent residue, peculiar smell, printing film, gas chromatograph 1 Significance Liquid dairy products, as the nutritional food needed by the public in daily life, its safety and quality directly affect the health of consumers During the shelf life of liquid dairy products, there are often quality problems such as bitter taste, flocculent precipitation, mold growth in milk bags, etc in addition, there will be packaging odor, which is similar to the smell of paint or other chemical reagents, and in serious cases, the odor will migrate to dairy products, It makes dairy products inedible The main reason for the peculiar smell is that the black-and-white film used in the liquid emulsion is usually printed on the outer surface of the black-and-white film packaging by using a special water and high temperature resistant surface printing ink At the same time, the resin raw materials and inks used in the manufacturing process and printing process of black-and-white film are prone to harmful small molecular substances or organic solvent residues Therefore, dairy enterprises should strengthen the detection of solvent residues in black-and-white film packaging for liquid milk Fig 1 black and white film packaging of liquid emulsion 2 For this test, please refer to GB / T 10004-2008 "plastic composite film for packaging, bag dry composite, extrusion composite" for the test method standard of solvent residue 3 Test sample black and white film packaging bag provided by a dairy factory 4 Test equipment: GC - 7800 gas chromatograph produced by Jinan Languang Electromechanical Technology Co., Ltd Fig 2 gc-7800 gas chromatograph 4.1 test principle gas chromatograph is a separation and analysis tool for multicomponent mixtures It uses inert gas as mobile phase and chromatographic column separation technology When a variety of analytical substances enter the chromatographic column, due to the different partition coefficient of each component in the chromatographic column, the flow speed of each component in the chromatographic column is different After a certain column length, the mixed components leave the chromatographic column and enter the detector respectively, and after detection, they are converted into electrical signals and sent to the data processing workstation, so as to complete the detection and analysis of the tested substances 4.2 scope of application (1) solvent residue: it is applicable to the solvent residue analysis and test of various plastic films, paper plastic composite films, cigarette packs and other materials for food and drug packaging (2) Purity analysis: it is applicable to the purity analysis of various solvents for packaging and printing (3) Moisture analysis: suitable for the analysis of moisture content of solvent used in packaging and printing industry (4) It needs special accessories or can be modified to expand the content analysis of vinyl chloride monomer 4.3 equipment parameters and instruments can be operated at constant temperature and programmed temperature The column chamber is equipped with a flexible back door automatic temperature control system, which can realize real near room temperature operation The temperature control range of the column chamber is room temperature + 3 ℃ ~ 400 ℃, the temperature control accuracy is better than ± 0.1 ℃, the deviation between the set temperature and the display temperature is not more than 1 ℃, and the deviation between the set temperature and the actual temperature is not more than 2% The instrument can be programmed to raise the temperature in 5 steps, the heating speed is 0.1 ~ 30 ℃ / min, and the repeatability of the programmed heating is not more than 2% The temperature control accuracy of gasification chamber and detection chamber is ± 0.1 ℃ within the temperature range of + 15 ℃ ~ 200 ℃, and ± 0.2 ℃ above 200 ℃ The basic configuration of the instrument is FID, the detection limit is not more than 2 × 10-11 g / S (benzene), the noise is not more than 0.025 MV, and the drift is not more than 0.15 MV / h The detector is designed by unit combination and adopts the plug and play extended control mode The configuration of hydrogen flame detector and thermal conductivity detector can be selected according to the user's analysis needs The instrument Zui can install four kinds of detectors at the same time The injection system can be equipped with a variety of injection devices, such as filling column head injection, capillary column split / non split injection with diaphragm cleaning function The response signal can reach 1500 MV wide range with good consistency, which can meet the needs of high purity sample analysis The excellent performance of chromatographic column box can realize the operation of room temperature + 3 ℃ near room temperature when the detector and gasifier are both at 200 ℃, and the instrument has good temperature programmed repeatability, which ensures the consistency of retention time of complex component sample analysis The instrument has the function of high temperature protection If the temperature control of any circuit exceeds a certain range of the set temperature (the set value is 20 ℃), the instrument will cut off the power supply for protection and give an alarm The instrument has the function of low pressure and cut-off of carrier gas circuit The unique operation control system software and hardware design, the instrument in the operation process of the system automatically implement the whole process of software monitoring, fundamentally put an end to the instrument temperature and operating parameters out of control phenomenon It realizes no fault over temperature protection, unique active over temperature protection function and dual hardware self-locking over temperature control structure to ensure the safe operation of the instrument when no one is on duty 5 Test process (1) set test parameters, click start, and gc-7800 gas chromatograph starts to conduct baseline balance (2) After the baseline of the instrument is stable, prepare mixed standard samples of different concentrations, inject them into a sealed headspace bottle, and place them in a constant temperature chamber of 80 ± 2 ℃ for 30 minutes (3) Take a certain amount of standard sample gas from the headspace bottle with a sampling needle and inject it into the chromatograph quickly, or configure an automatic sampler to inject the sample automatically Draw the standard curve of peak area and corresponding concentration of each reference material (4) Cut the 0.2 M 2 sample into 10 m m × 30 mm pieces, put it into a clean preheated bottle at 80 ± 2 ℃, seal it quickly, and put it in a constant temperature chamber at 80 ± 2 ℃ for 30 min Pay attention to prevent the sample from being polluted during sample preparation (5) Take a quantitative sample gas from the sample bottle after constant temperature with a sampling needle, and inject it into the chromatograph quickly, or configure an automatic sampler to inject the sample automatically (6) According to the peak area of the sample, read the concentration of the corresponding component from the standard curve 6 The results showed that the total amount of solvent remained in the black-and-white film packaging sample was 7.5792 mg / M 2, and the benzene was 0.1411 mg / m2 7 Conclusion according to GB / T 10004-2008 packaging plastic composite film, bag dry method composite and extrusion composite, the total amount of solvent residue is less than or equal to 5.0 mg / M 2, among which benzene solvent shall not be detected (< 0.01 mg / m2) Therefore, the total amount of residual solvent in the sample tested in this paper exceeds the standard, and the peculiar smell of the sample is mainly caused by the high residual solvent Gc-7800 gas chromatograph has the advantages of high accuracy, good accuracy and safety in use in testing solvent residues It can truly reflect the hygienic chemical properties of packaging materials and help dairy enterprises to solve the problem of packaging odor In addition to black-and-white film, gc-7800 gas chromatograph can also be used to test the residual solvents in plastic composite film, aluminum-plastic composite film, aluminum-plated composite film, paper based composite film, printed single-layer film and other packaging materials Labthink Languang has been committed to providing professional testing services and equipment for customers around the world Over the years, it has provided thousands of solvent residue testing services for customers around the world, providing customers with reliable technical solutions Labthink is looking forward to enhancing technical exchanges and cooperation with users in various industries.