Melamine, commonly known as melamine and protein essence, has a molecular formula of CthreeHsixNsixIUPAC, named as "1,3,5-triazine-2,4,6-triamine", is a triazine nitrogen containing heterocyclic organic compound, which is used as chemical raw material.It is white monoclinic crystal, almost tasteless, harmful to the body, and cannot be used for food processing or food additives.
On October 27, 2017, the list of carcinogens released by the International Agency for Research on Cancer of the World Health Organization (WHO) was preliminarily sorted out for reference, and melamine was included in the list of Category 2B carcinogens.[5]
The abscissa represents the mass charge ratio (m/z) value of the ion. The mass charge ratio increases from left to right. For the ion with single charge, the value represented by the abscissa is the mass of the ion.
Molecular structure data
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Molar refractive index: 33.23
Molar volume (cmthree/mol）：75.9
Isotonic specific volume (90.2K): 267.2
Surface tension (dyne/cm): 153.2
Polarization (10-24cmthree）：13.17[4]
Calculate chemical data
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Reference value for drainage parameter calculation (XlogP): None
Number of hydrogen bond donors: 3
Number of hydrogen bond receptors: 6
Number of rotatable chemical bonds: 0
Number of tautomers: 5
Topological molecular polar surface area: 117
Number of heavy atoms: 9
Surface charge: 0
Complexity: 63.3
Number of isotope atoms: 0
Determine the number of atomic structure centers: 0
Number of uncertain atomic structure centers: 0
Determine the number of chemical bond structure centers: 0
Number of uncertain chemical bond structure centers: 0
Number of covalent bond units: 1[4]
purpose
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Melamine is an important nitrogen heterocyclic organic chemical raw material, which is mainly used as the main raw material for manufacturing melamine formaldehyde resin (MF), organic element analysis reagent, organic and resin synthesis, tanning agent and filler for leather processing, wood, plastic, paint, paper making, textile, leather, electrical, pharmaceutical and other industries, as well as flame retardantFormaldehyde cleaner, fertilizer, etc.[6]
Melamine is the most commonly used gas source for intumescent flame retardants, as well as the raw material for preparing many intumescent flame retardant components (such as various phosphates, cyanuric acid salts, phosphates). It is also often compounded with other flame retardants to retard a variety of plastics and other polymers, such as the combination with organic phosphate esters to retard polyurethane foam.[8]
First aid measures
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Skin contact: Take off contaminated clothes and wash with plenty of flowing water.
Eye contact: Lift the eyelid and flush with flowing water or physiological saline.Get medical attention.
Inhalation: leave the site to fresh air.Get medical attention.
Ingestion: drink enough warm water to induce vomiting.Get medical attention.
Fire fighting measures
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Hazard characteristics: It will release highly toxic cyanide gas after being decomposed by heat.
Extinguishing method: firefighters must wear filter type gas masks (full face masks) or isolated respirators, wear full body fire and gas clothing, and extinguish the fire upwind.Move the container from the fire site to an open place as far as possible.
Leakage emergency treatment
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Isolate the leakage contaminated area and restrict access.It is recommended that emergency personnel wear dust masks (full face masks) and gas suits.Collect dry, clean and covered containers with clean shovels and transfer them to a safe place.In case of large leakage, collect and recycle or transport to waste disposal site for disposal.
Handling and storage
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Operation precautions: closed operation, full ventilation.Operators must be specially trained and strictly abide by the operating procedures.It is recommended that operators wear self-priming filter type dust mask, chemical safety goggles, anti poison penetration work clothes and rubber gloves.Avoid dust generation.Avoid contact with oxidants and acids.Load and unload gently during transportation to prevent damage to packaging and containers.Provide leakage emergency treatment equipment.Empty containers may leave harmful substances.
Precautions for storage: store in a cool and ventilated warehouse.Keep away from kindling and heat sources.It shall be stored separately from oxidants and acids, and mixed storage is strictly prohibited.The storage area shall be equipped with appropriate materials to contain leakage.
security information
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Safety terminology
S36/37：Wear suitable protective clothing and gloves.
Wear appropriate protective clothing and gloves.
Risk terminology
R20/21：Harmful by inhalation and in contact with skin.
Harmful by inhalation and skin contact.
R44：Risk of explosion if heated under confinement.
Explosion hazard due to enclosed heating.
toxicity
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acute toxicity
Melamine oral LD in ratsfifty3100 ～ 3300mg/kg body weight, oral LD in micefifty4550mg/kg body weight, belonging to low toxicity compound.The toxicity to male animals is greater than that to female animals, and long-term high dose intake will cause bladder stones, hypertrophy and inflammation.However, according to the investigation of the US Food and Drug Administration (FDA) on the poisoning deaths of pet cats and dogs in the United States in 2007, it was found that these pets suffered from acute renal failure after ingesting melamine contaminated pet food, so the acute toxicity of melamine should be re cautious.
Chronic toxicity
FAO/WHO believes that long-term exposure of animals to melamine may cause reproductive damage, bladder or kidney stones, bladder cancer, etc.Animal experimental studies found that feeding male rats with 4500 mg/kg or 263 mg/(kg body weight · d) high dose of melamine for 2 years would cause bladder stones and increase the risk of malignant tumors in the bladder and urethra.However, female rats and male or female mice did not suffer from bladder cancer.The tumor caused by high dose of melamine is highly related to bladder stones.
Hazards to human health
Long term ingestion of melamine may cause damage to human reproductive capacity, bladder or kidney stones, bladder cancer, etc. For breast-feeding infants who drink less water and have narrow kidneys, stones are more likely to form, and serious cases may even lead to renal failure or death.There is an obvious dose effect relationship between the dose of melamine and clinical diseases.Life Science magazine reported that pure melamine is slightly toxic, but melamine is often mixed with cyanuric acid in the production process;Or after melamine enters the human body, it will partially hydrolyze into cyanuric acid in the strong acidic environment of the stomach.Melamine and cyanuric acid can form a large network structure (hydrogen bond structure). After ingestion, due to the effect of gastric acid, melamine and cyanuric acid are separated, absorbed by the small intestine, enter the blood circulation, and finally enter the kidney.In the kidney cells, the two combine again and deposit to form stones, which block the renal tubules and eventually lead to renal failure.For larger adults, due to their strong metabolic capacity, they often drink water, and stones are not easy to form.However, infants and young children drink less water and have small kidneys, which are vulnerable to stone damage.Melamine is harmful to human body and is strictly prohibited to be used in food and animal feed.In the process of food processing, transportation, storage and sales, melamine may pollute food from all aspects.The state stipulates that the limit of melamine entering food from packaging materials shall not exceed 30mg/kg.[6]
Contaminated food
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source
Add artificial fraud
Melamine, as a feed additive, hydrolyzes slowly in ruminant animals and is not metabolized as completely as other non protein nitrogen compounds. On the contrary, it may cause harm to animals' kidneys, so it is prohibited to add it to feed.
For a long time, the "Kjeldahl method" has been used to determine the protein content in food, that is, the protein content in food is indirectly calculated by measuring the nitrogen content of food multiplied by 6.25.According to the molecular formula of melamine, its nitrogen content can be calculated to be about 66%. If 0.1g of melamine is added to every 100g of milk, the protein content of milk can theoretically be increased by 0.625%. Therefore, melamine is also known as "protein essence", which is illegally added to milk and other foods to increase the so-called "protein" content.Moreover, melamine is white and tasteless, which is difficult to be found after being mixed into food. Driven by interests, illegal traders add it to food to improve the apparent protein content in food detection.[6]
Melamine formed by heating urea during milk powder production
The purpose of adding urea to raw milk is the same as that of adding melamine, but it is just an artificial illusion that the protein content meets the national standard.The production process of milk powder requires high temperature dehydration and drying to make powder, and the urea in it can form melamine after dehydration and condensation, which is one of the reasons for the excessive content of melamine in animal food.[6]
Other ways
Because melamine is widely used in the production of food containers, drug capsules, pesticides, paper, coatings, decorative materials, etc., it is easy for trace amounts of melamine to enter food.As early as 1987, Japan found that food containers would migrate out of melamine and enter the human food chain.According to WHO estimates, the content of melamine transferred from packaging materials to infant food can reach up to 0.5mg/kg.Porcelain like tableware is made from melamine resin powder by heating and pressure casting. It has stable chemical structure after processing and molding. Qualified melamine tableware has not been detected melamine precipitation after long-term use, so it is safe.However, attention should be paid to the method of use.Because the main component of porcelain like tableware is melamine, which can be dissolved in glycerin, pyridine and other organic solvents, and melamine may decompose at high temperatures, try to avoid contact with grease, avoid using at high temperatures, and it is better not to use it in a microwave oven.The research shows that when the temperature is higher than 220 ℃, the melamine resin can be degraded, and the degradation rate increases with the increase of temperature, and formaldehyde and melamine monomer are released.Therefore, imitation porcelain tableware should be used below 200 ℃.
Melamine is also the degradation product of the commonly used pesticide cyromazine, so there may be melamine residues in vegetables, grains and other agricultural products.In addition, if the feed is contaminated by melamine, it can also be fed into agricultural products such as eggs through the intake of animals.[6]
to guard against
To prevent melamine from polluting food, we should focus on the links of feed, feeding, milking, storage, transportation and milk processing.More efforts should be made to crack down on illegal users of food.
Prevent feed from being polluted by melamine
Feed manufacturers and self blending farmers should focus on the purchase of raw materials, especially protein raw materials.The supplier is required to provide melamine test qualification report, and strengthen inspection and self inspection.The farmers who buy the formula feed from the feed manufacturer mainly ask the manufacturer for the finished product test report.In addition, feed manufacturers are strictly prohibited to add melamine and other pollutants in feed formulation.
Prevention of melamine contamination in the feeding process
It is strictly prohibited to purchase feed (including drinking water), raw materials and supplies containing melamine.
Prevent melamine contamination during milking, storage and transportation
Strictly control, do not use any articles that may contain melamine, and do not add melamine and other pollutants to milk.with
In the process of milking, storage and transportation, the equipment and packaging materials contain melamine, which will prevent the milk from being polluted.
Prevention of melamine pollution in dairy processing
Strengthen the detection of raw milk purchase to ensure that raw milk does not contain melamine.In addition, strictly purchase any supplies that may contain melamine.It is also prohibited to illegally add melamine and other pollutants to dairy products.[7]
Limited standard
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Chinese Standards
On April 6, 2011, the Announcement on the Limit Value of Melamine in Food: Melamine is neither a food raw material nor a food additive, and it is prohibited to add it to food artificially.If melamine is artificially added to food, legal responsibility shall be investigated according to law.As a chemical raw material, melamine can be used in the production of plastics, coatings, adhesives and food packaging materials.Data shows that melamine may enter food from the environment, food packaging materials and other ways, and its content is very low.In order to ensure human health and food safety, according to the provisions of the Food Safety Law and its implementation regulations, on the basis of summarizing the implementation of the announcement on the temporary management limit value of melamine in milk and dairy products (No. 25 announcement in 2008), and considering that the Codex Alimentarius Commission has proposed the limit standard of melamine in food, the limit value of melamine in food in China is hereby formulated.It is hereby announced as follows:
The limit of melamine in infant formula is 1mg/kg, and the limit of melamine in other foods is 2.5mg/kg. Food above the above limit shall not be sold.
The above provisions shall come into force as of the date of promulgation.The announcement on the temporary management limit value of melamine in milk and dairy products (Announcement No. 25 of 2008) shall be repealed at the same time.
international standard
On July 2, 2012, the 35th session of the Codex Alimentarius Commission reviewed and approved the limit standard of melamine in liquid infant formula, specifically: the limit of melamine in liquid infant formula is 0.15mg/kg.
On July 5, 2012, the Codex Alimentarius Commission, which is responsible for the formulation of food safety standards by the United Nations, set a new standard for the content of melamine in milk. In the future, the content of melamine in every kilogram of liquid milk should not exceed 0.15 mg.The Codex Alimentarius Commission said that the new standard for melamine content would help national governmentsThe government will better protect consumers' rights and health.[2]
In 2008, a lot of foodsanlu group The baby who produced the milk powder was found to haverenal calculusAnd then melamine, the chemical raw material, was found in its milk powder.According to the published figures, as of September 21, 2008, there were 39965 infants who had received outpatient treatment consultation and had recovered due to the use of infant milk powder, 12892 infants were in hospital, 1579 had been cured and discharged before, and 4 had died. As of September 25, there were 5 infants in Hong Kong and 1 infant in Macao who had been diagnosed with disease.The incident has aroused great concern of all countries and concerns about the safety of dairy products.
On January 22, 2009, the Intermediate People's Court of Shijiazhuang City, Hebei Province, issued a judgment in the first instance, and the former chairman of SanluTian WenhuaWang Yuliang, Hang Zhiqi and Wu Jusheng, senior managers of Sanlu Group, were sentenced to life imprisonment of 15 years, 8 years and 5 years respectively.Sanlu Group, as the unit defendant, committedCrime of producing and selling fake and inferior productsAnd was fined more than 49.37 million yuan.Dairy farmers suspected of manufacturing and selling melamineZhang Yujun, Gao Junjie andGeng JinpingThree people were sentencedDeath penalty: Xue Jianzhong is sentenced to life imprisonment, Zhang Yanjun is sentenced to 15 years' imprisonment, Geng Jinzhu is sentenced to 8 years' imprisonment, and Xiao Yu is sentenced to 5 years' imprisonment.[1]
Investigate and deal with Boda Food
On July 30, 2014, the Guangdong Provincial Public Security Department held a press conference.He Guangping, the deputy director of the Guangdong Provincial Public Security Department, said that the department had recently deployed the Chaozhou police to investigate and deal with the case of Chaozhou Boda Food Co., Ltd. suspected of producing and selling food that did not meet food safety standards, successfully captured Yang Mouwu, the operator who produced and sold yoghurt flakes containing "melamine", and seized 12.05 tons of finished yoghurt flakes produced by the company,13.5 tons of semi-finished yogurt chip sugar.After in-depth investigation, the case is a major and complex case involving many places in other provinces. Guangdong Public Security Department and the Times asked the Ministry of Public Security to launch a nationwide cluster campaign, organizing 12 provinces, cities and districts across the country to completely destroy the entire criminal network.
On August 1, 2014, Guangdong Food and Drug Administration held a press conference on August 1 to report that the bureau, together with Guangdong police, successfully solved the case of Chaozhou Boda Food Co., Ltd. suspected of producing and selling yogurt flakes containing "melamine", and seized 12.05 tons of finished yogurt flakes and 13.5 tons of semi-finished yogurt flakes.The police have detained five suspects involved in the case and issued arrest warrants.[3]
