Melamine

Molecular three-dimensional model catalog

Physical and chemical properties

Toxicity hazards and diagnosis and treatment

Human body's response to melamine Tolerance standard

Principle of fake protein

The effect of adding melamine to milk

Synthesis process

Related disease cases

How to detect whether milk products contain melamine at home

Professional chemical detection method to test melamine

Professional chemical detection method to test melamine

Melamine (English name Melamine) is a triazine nitrogen-containing heterocyclic organic compound and an important nitrogen-containing heterocyclic organic chemical raw material. Triamine for short, also known as 2,4,6-triamino-1,3,5-triazine, 1,3,5-triazine-2,4,6-triamine, 2,4,6-triamino Urea, melamine, melamine, cyanuric triamide, molecular formula C3N6H6, C3N3(NH2)3, molecular weight 126.12.

More English names: 1,3,5-Triazine-2,4,6-triamine; 2,4,6-Triamino-1,3,5-triazine; 2,4,6- Triamino-s-triazine; Aero; Cyanuramide; Cyanuric triamide; Cyanurotriamide; Cyanurotriamine; DG 002 (amine); Hicophor PR; Isomelamine; Melamine; NCI-C50715; Pluragard; Pluragard C 133; s-Triazine, 2, 4, 6- triamino-; Teoharn; Theoharn; Virset 656-4;

CAS No. 1087815041876554434567757431683795557037119694977-27-2

Edit the physical and chemical properties of this paragraph

The properties of melamine are pure White monoclinic crystal, odorless, density 1.573g/cm3 (16℃). Melting point under normal pressure is 354℃ (decomposition); rapid heating and sublimation, sublimation temperature is 300℃. Soluble in hot water, slightly soluble in cold water, very slightly soluble in hot ethanol, insoluble in ether, benzene and carbon tetrachloride, soluble in methanol, formaldehyde, acetic acid, hot ethylene glycol, glycerin, pyridine, etc. Low toxicity. It is relatively stable under normal circumstances, but may decompose and release cyanide at high temperatures.

It is weakly alkaline (pKb=8) and can form melamine salts with hydrochloric acid, sulfuric acid, nitric acid, acetic acid, oxalic acid, etc. In neutral or slightly alkaline conditions, it condenses with formaldehyde to form various hydroxymethyl melamines, but in slightly acidic conditions (pH value 5.5 to 6.5), it undergoes a polycondensation reaction with methylol derivatives to form resin products. When hydrolyzed by strong acid or strong alkali aqueous solution, the amine group is gradually replaced by the hydroxyl group, first forming ammeline, then further hydrolyzing to form ammelide, and finally forming cyanuric acid.

Structural formula Main uses Melamine is a basic organic chemical intermediate product with a wide range of uses. The most important use is as a raw material for the production of melamine formaldehyde resin (MF). Melamine can also be used as a flame retardant, water reducing agent, formaldehyde cleaner, etc. This resin has higher hardness than urea-formaldehyde resin, is non-flammable, is water-resistant, heat-resistant, aging-resistant, arc-resistant, chemical-resistant, has good insulation properties, glossiness and mechanical strength, and is widely used in wood, plastics, coatings, papermaking, and textiles. , leather, electrical, pharmaceutical and other industries. Its main uses are as follows:

(1) Decorative panels: they can be made into fireproof, earthquake-resistant, heat-resistant laminates, bright-colored, strong and heat-resistant decorative panels for aircraft, ships and furniture. veneer panels and fireproof, earthquake-resistant and heat-resistant house decoration materials.

(2) Coating: After etherification with butanol and methanol, it can be used as a bonding agent for advanced thermosetting coatings and solid powder coatings, and can be used to produce metal coatings and high-grade amino resin decorative paints for vehicles and electrical appliances.

(3) Molding powder: After mixing, granulating and other processes, it can be made into melamine plastic, which is non-toxic and stain-resistant. It can still maintain good electrical properties when wet and can be made into white, durable plastic. High-grade insulation materials such as beaten daily utensils, sanitary ware, melamine tableware, and electrical equipment.

(4) Paper: After etherification, it can be used as a paper treatment agent to produce high-grade paper such as anti-wrinkle, anti-shrink, and non-corruptible banknotes and military maps.

(5) Mixing melamine formaldehyde resin with other raw materials can also produce fabric finishing agents, leather tanning agents, polishing agents and water-resistant agents, rubber adhesives, combustion accelerants, high-efficiency Cement water reducing agent, steel desalination agent, etc.

Edit this section Toxicity Hazards, Diagnosis and Treatment

Currently, melamine is considered to be mildly toxic, and the oral LD50 of rats is greater than 3 g/kg body weight. According to an experimental report in 1945, no obvious poisoning was observed after feeding large doses of melamine to rats, rabbits and dogs. Long-term ingestion of melamine in animals can cause damage to the reproductive and urinary systems, bladder and kidney stones, and can further induce bladder cancer. The third volume of the "International Chemical Safety Manual" and the International Chemical Safety Card jointly compiled by the International Program on Chemical Safety and the European Commission in 1994 only state that long-term or repeated intake of large amounts of melamine may have effects on the kidneys and bladder. Lead to the formation of stones. However, the preliminary investigation results of the 2007 pet food contamination incident in the United States concluded that wheat protein powder adulterated with ≤6.6 melamine was the cause of pet food poisoning, which cast doubt on the conclusion that the above-mentioned toxicity was mild. However, for safety reasons, tableware generally made of melamine will be marked "not for use in microwave ovens."

On September 12, 2008, the Ministry of Health of the People's Republic of my country released the "Diagnosis and Treatment Plan for Urinary System Stones in Infants and Young Children Related to Consumption of Contaminated Sanlu Brand Infant Formula Milk Powder". Relevant parties can refer to it.

The plan points out that most stones involve the bilateral collecting system and bilateral ureters, which is different from the clinical manifestations of adult urinary system stones. Multiple stones have a higher probability of affecting renal function. Since many children do not have the ability to complain of symptoms, parents need to strengthen observation of the children involved. Relying on abdominal B-ultrasound and/or CT examination can help determine the diagnosis early. In terms of treatment, there is currently no specific antidote for the toxic effects of melamine. Clinical practice mainly relies on symptomatic and supportive treatment. If necessary, surgical intervention can be considered to relieve the risk of long-term renal damage in children. Early diagnosis and early treatment are the keys to a speedy recovery for children.

Edit this section on human body tolerance standards for melamine

Melamine is a low-toxic chemical raw material. Animal experiment results show that it is metabolized quickly in the animal body and does not persist, mainly affecting the urinary system.

There is an obvious dose-effect relationship between the dosage of melamine and clinical diseases. The maximum tolerated level of melamine in infants is 15 mg per kilogram of milk powder. A risk assessment conducted by experts on contaminated infant formula shows that, taking a 7-kg infant as an example, assuming a daily intake of 150 grams of milk powder, the safety predetermined value, that is, the maximum tolerated dose, is 15 mg/kg of milk powder.

According to the standards of the US Food and Drug Administration, the tolerable daily intake of melamine is 0.63 mg/kg of body weight per day.

Edit the principle of fake protein in this paragraph

Due to the shortcomings of protein content testing methods in the food and feed industry, melamine is often used as a food additive by unscrupulous businessmen to improve the protein content in food testing. Content index, so melamine is also called "protein essence".

Protein is mainly composed of amino acids, and its nitrogen content generally does not exceed 30, while the nitrogen content of the molecular formula of melamine is about 66%. The common protein testing method "Kjeldahl method" estimates protein content by measuring nitrogen content. Therefore, adding melamine will make the protein test content of food higher, thereby making inferior food pass the test of food inspection agencies.

Some people estimate that the cost of using melamine to increase the tested protein content by one percentage point in plant protein powders and feeds is only 1/5 of that of real protein raw materials. As a white crystalline powder, melamine has little smell or taste and is difficult to detect after being adulterated.

Milk powder incident: The protein content of various brands of milk powder is 15-20 (I saw some labeled 10-20 on the packaging in the supermarket at night), and the average nitrogen content of the protein is 16. If the protein content of a certain qualified milk is 2.8, the nitrogen content is 0.44. If the protein content of a certain qualified milk powder is 18, the nitrogen content is 2.88. The nitrogen content of melamine is 66.6, which is 151 times that of milk and 23 times that of milk powder. Adding 0.1 gram of melamine per 100g of milk can increase protein by 0.4.

Slightly soluble means that 1g (ml) of the solute can be dissolved in 100 to less than 1000ml of solvent. Melamine is slightly soluble in water. No experimental data has been found on its solubility in oil-in-water emulsions such as milk. It should be The solubility is better than that of water, yet to be verified.

Testing plan

In the existing national standards for milk powder testing, protein, fat, bacteria, etc. are mainly tested. Melamine is a chemical raw material and is not allowed to be added to food, so the existing standards will not include corresponding content. That is to say, there is currently no national standard for melamine testing. Therefore, TV Rheinland Group refers to the US Food Chemical Code (FCC) melamine HPLC-UV quantitative method, and can also use HPLC/MS detection methods (laboratory methods) for baby food, pet food, feed and their raw materials ( Including starch, rice protein, corn gluten, gluten, grain and oil, etc.) to carry out melamine testing business, and the test results are authoritative.

Edit this paragraph about the effect of adding melamine to milk

Milk powder is toxic because it contains melamine, which may be added directly to the milk powder or added to the raw milk.

Melamine is added to milk and milk powder, mainly because it can impersonate protein.

Foods must be tested for protein content in accordance with regulations. If there is not enough protein, it means that the milk has been mixed with too much water, or that there is too much powder from other things in the milk powder.

However, protein is too difficult to detect, so biochemists came up with a lazy way: because protein contains nitrogen, so as long as the nitrogen content in food is measured, the nitrogen content can be calculated. protein content.

Therefore, it is difficult to detect that the protein of milk powder added with melamine is unqualified. This is the false protein of melamine

Edit the synthesis process of this paragraph

Melamine was the earliest It was synthesized by Liebig in 1834. The early synthesis used the dicyandiamide method: calcium cyanamide (CaCN2) was prepared from calcium carbide (CaC2). Calcium cyanamide was hydrolyzed and dimerized to form dicyandiamide (dicyandiamide), which was then heated and decomposed to prepare melamine. . At present, the dicyandiamide method has been eliminated due to the high cost of calcium carbide. Compared with this method, the urea method is low in cost and is currently used more often. Urea uses ammonia as the carrier and silica gel as the catalyst. It boils and reacts at a temperature of 380-400°C. It first decomposes to generate cyanic acid, and further condenses to generate melamine.

6 (NH2)2CO → C3H6N6 6 NH3 3 CO2

The generated melamine gas is cooled and captured to obtain the crude product, which is then dissolved to remove impurities and recrystallized to obtain the finished product. . The production of melamine by urea method consumes about 3800kg of urea and 500kg of liquid ammonia per ton of product.

According to different reaction conditions, the melamine synthesis process can be divided into high-pressure method (7-10MPa, 370-450℃, liquid phase) and low-pressure method (0.5-1MPa, 380-440℃, liquid phase) and atmospheric pressure method (lt; 0.3MPa, 390°C, gas phase).

Most foreign melamine production processes are named after technology development companies, such as BASF Process in Germany, Chemical Linz Process in Austria, Lurgi Process, and Allied Signal Chemical Company in the United States. Chemical method (Allied Signal Chemical), Japan's new Nissan Process (Nissan Process), the Netherlands' Stamicarbon method (DSM method), etc. These production processes can be basically divided into three processes: high pressure method, low pressure method and normal pressure method according to different synthesis pressures. Currently, the most technologically advanced and competitive ones in the world include Japan's Nissan method and Italy's Allied-Eurotechnica's high-pressure method, the Netherlands' DSM low-pressure method and Germany's BASF's atmospheric pressure method.

my country's melamine production enterprises mostly use the semi-dry atmospheric pressure process. This method uses urea as the raw material below 0.1MPa at about 390°C, uses silica gel as the catalyst to synthesize melamine, and makes the melamine sublimate. Crystallize in the vessel, and the crude product is made into finished product after dissolution, filtration, and crystallization.

Edit related disease cases in this paragraph

In 2007, a pet food contamination incident broke out in the United States. Subsequent investigations showed that wheat protein powder adulterated with melamine ≤6.6 was the cause of pet food poisoning.

In September 2008, an incident involving contamination of Sanlu infant milk powder broke out in China, causing infants and young children who consumed the contaminated milk powder to develop kidney stones. The reason was that the milk powder contained melamine.

The General Administration of Quality Supervision, Inspection and Quarantine of the People’s Republic of China has recently launched an emergency nationwide inspection of melamine content in infant milk powder. This special inspection investigated the remaining 109 companies and inspected 491 batches of products from these companies. Phased inspection results showed that 69 batches of products from 22 infant milk powder manufacturers were detected with varying amounts of melamine.

List of companies detecting melamine in infant formula milk powder

Serial number Nominal company product name Number of samples unqualified Maximum melamine content mg/kg

1 Shijiazhuang Sanlu Group Co., Ltd. Sanlu brand infant formula milk powder 11 11 2563.00

2 Shanghai Panda Dairy Co., Ltd. Panda Kebao brand infant formula milk powder 5 3 619.00

3 Qingdao Shengyuan Dairy Co., Ltd. Shengyuan brand infant formula milk powder 17 8 150.00

4 Shanxi Gucheng Dairy Group Co., Ltd. Gucheng brand infant formula milk powder 13 4 141.60

5 Jiangxi Guangming Hero Dairy Co., Ltd. Hero Brand Infant Formula Milk Powder 2 2 98.60

6 Baoji Huimin Dairy (Group) Co., Ltd. Huimin Brand Infant Formula Milk Powder 1 1 79.17

7 Inner Mongolia Mengniu Dairy (Group) Co., Ltd. Mengniu brand infant formula milk powder 28 4 68.20

8 Sino-Australian joint venture Dogado Dairy (Tianjin) Co., Ltd. Keqi brand infant formula milk powder 1 1 67.94

9 Guangdong Yashili Group Co., Ltd. Yashili brand infant formula milk powder 30 10 53.40

10 Hunan Peiyi Dairy Co., Ltd. Nanshan Beiyi brand infant formula milk powder 3 1 32.00

11 Heilongjiang Province Qining Dairy Co., Ltd. Infant formula milk powder 2-stage base powder 1 1 31.74

12 Shanxi Yashili Dairy Co., Ltd. Yashili brand infant formula milk powder 4 2 26.30

13 Shenzhen Jinbishi Dairy Co., Ltd. Jinbishi Brand Infant Formula Milk Powder 2 2 18.00

14 Shi En (Guangzhou) Infant Nutrition Products Co., Ltd. En brand infant formula milk powder 20 4 17.00

15 Guangzhou Jinding Dairy Factory Jinding brand infant formula milk powder 3 1 16.20

16 Inner Mongolia Yili Industrial Group Co., Ltd. Yili brand Children's formula milk powder 35 1 12.00

17 Yantai Aomeiduo Nutritional Products Co., Ltd. Aomeiduo brand infant formula milk powder 6 6 10.70

18 Qingdao Suokang Nutrition Technology Co., Ltd. Aikeding brand infant formula milk powder 3 1 4.80

19 Xi'an Yanliang District Baiyue Dairy Co., Ltd. Yubao brand infant formula milk powder 3 1 3.73

20 Yantai Leilei Dairy Co., Ltd. Leile brand infant formula milk powder 3 3 1.20

21 Shanghai Baoanli Dairy Co., Ltd. Baoanli brand infant formula milk powder 1 1 0.21

22 Fuding City Morning Guan Dairy Co., Ltd. Congerzhuang brand infant formula milk powder 1 1 0.09

Batch list of melamine detected in liquid milk

Company serial number Production company Product name Specification Model Trademark Production date /Batch Melamine (mg/kg)

Mengniu 1 Mengniu (Wuhan) Youzhiyou Dairy Co., Ltd. Walnut milk 200ml/bag Youzhiyou 20080910 0.765

Mengniu 2 Inner Mongolia Mengniu Dairy (Group) Co., Ltd. Mengniu High Calcium Low-fat Milk 250ml/box Mengniu 2008.08.07 0.8

Mengniu 3 Inner Mongolia Mengniu Dairy (Group) Co., Ltd. Full-fat sterilized pure milk 250ml/box Mengniu 2008.09. 01 1.0

Mengniu 4 Inner Mongolia Mengniu Dairy (Group) Co., Ltd. High Calcium Low-fat Milk 250ml/box Mengniu 2008.08.01 1.5

Mengniu 5 Inner Mongolia Mengniu Dairy (Group) Co., Ltd. Company breakfast milk (wheat flavor) 250ml/pack Mengniu

20080814 1.9

Mengniu 6 Inner Mongolia Mengniu Dairy (Group) Co., Ltd. Mengniu Breakfast Milk 250ml/box Mengniu 2008.07.26/x 2.57

Mengniu 7 Inner Mongolia Mengniu Dairy (Group) Co., Ltd. Company highlights 250ml/box Mengniu 20080728/W206 3.17

Mengniu 8 Mengniu Dairy (Beijing) Co., Ltd. Xylitol yogurt 2kg/bottle Mengniu 20080806 3.52

Mengniu 9 Inner Mongolia Mengniu Dairy (Group) Co., Ltd. High Calcium Low Fat Milk 243ml (250g)/bag Mengniu 20080908/C206/GAfb 4.2

Mengniu 10 Mengniu Dairy (Maanshan) Co., Ltd. Mengniu Large Fruit Yogurt 160g/box Mengniu M20080903 6.8 (A sample)

Mengniu 11 Mengniu Dairy (Maanshan) Co., Ltd. Mengniu large fruit yogurt 160g/box Mengniu M20080903 7 (B sample)

Yili 1 Jinan Yili Dairy Co., Ltd. Company Yili Mango Yellow Peach Yogurt 125g/box Yili 2008.09.07 0.69

Yili 2 Inner Mongolia Yili Industrial Group Co., Ltd. Yogurt (Papaya Sweet Orange) 125g/bottle Yili 20080903 1.02

Yili 3 Inner Mongolia Yili Industrial Group Co., Ltd. pure milk 220ml/bag Yili 2008.09.13 2.2

Yili 4 Inner Mongolia Yili Industrial Group Co., Ltd. skimmed milk 250ml/box Yili 20080820 2.9

Yili 5 Inner Mongolia Yili Industrial Group Co., Ltd. pure milk 220ml/bag Yili 20080905MIAC6 5.5

Yili 6 Inner Mongolia Yili Industrial Group Co., Ltd. pure milk 242ml/bag Yili 20080906/LIA09 8

Yili 7 Inner Mongolia Yili Industrial Group Co., Ltd. high-calcium low-fat milk 250ml/box Yili 20080819 8.4

Guangming 1 Beijing Guangming Jianneng Dairy Co., Ltd. Guangming yogurt (original) 180g/bag Guangming 2008.09.12 0.6

Guangming 2 Wuhan Guangming Dairy Co., Ltd. Original yogurt 180g/box Guangming 2008-09-13 3.41

Guangming 3 Beijing Guangming Jianneng Dairy Co., Ltd. Original yogurt 100g/cup Guangming 20080910A 3.5

Guangming 4 Beijing Guangming Jianneng Dairy Co., Ltd. Large Fruit Strawberry Yogurt 450g/box Guangming 20080902BC 4.8

Guangming 5 Guangming Dairy Co., Ltd. Probiotic·Excellent Yoghurt (Original Flavor) 190g/can Guangming B20080908C 5.65

Guangming 6 Beijing Guangming Jianneng Dairy Co., Ltd. Yogurt Yogurt (original flavor) 580g/bottle Guangming B20080909A 8.6

A case of illegal addition of melamine

In 2007, the Shenzhen Inspection and Quarantine Bureau detected melamine in three batches of "Aizu Brand" ornamental fish feed imported from Taiwan, and the melamine content was relatively high, respectively 0.35 g/kg, 0.47g/kg, and 0.51g/ kg. These 3 batches of fish feed*** are 846 kilograms and worth US$1,016.

In 2007, Fujian, Tianjin, Shandong, and Zhuhai Inspection and Quarantine Bureaus detected positive results for melamine in fishmeal imported from Malaysia, Thailand, and Peru (HS codes were all 2301201000), and the imported fishmeal has been returned in accordance with the law.

According to official news from the U.S. Food and Drug Administration (FDA), the U.S. FDA has found melamine in feed produced in the United States for the first time, and relevant companies have begun to voluntarily recall related products. Feed additives containing melamine were sourced from Tembec BTLSR Inc. of Toledo, Ohio, and Uniscope Inc. of Johnstown, Colorado. Tembec produces AquaBond and Aqua-Tec II adhesives, mainly for export, and also provides raw materials for the production of Xtra-Bond adhesives to Uniscope. The Xtra-Bond adhesives produced by Uniscope are mainly supplied to the US market. The above-mentioned binders are mainly used to produce pellet feed for cattle, sheep, goats, fish and shrimp. Tembec confirmed that melamine was added to the product formula in order to increase the viscosity of the pellet feed. However, melamine is prohibited from being used as an animal or fish/shrimp feed additive in the United States.

In 2007, the Beijing Inspection and Quarantine Bureau detected positive melamine in pet food imported from Australia (HS code: 2309101000), and returned the imported pet food in accordance with the law.

How does Duan family detect whether milk products contain melamine

(1) Test whether liquid milk contains melamine

Melamine is slightly soluble in water. At room temperature, The solubility in water is only 0.33, which means that only 0.33 grams of melamine can be added to 100 grams of milk. The protein content in 100 grams of milk is about 3 grams, which means that after adding melamine to 100 grams of milk, if water is added falsely, only 10 grams of water can be added. For counterfeiting, the profit is too small and the risk is high. In addition, the most important thing is that the aqueous solution of melamine is alkaline. If melamine is added to milk, its pH value will be close to 8, which can be easily measured with a pH meter.

It is much easier to add melamine in the milk powder manufacturing process. This is because the solubility of melamine increases rapidly with the increase of temperature. At 100°C, the solubility of melamine in water reaches 5.14. In the manufacturing process of milk powder, sterilization and spray granulation are required, and the temperature is around 100°C.

There is an easier way to prove who added the melamine, that is to measure the melamine content in milk powder from different batches and production dates. If the difference is very small, then it can be proved that melamine was added during the production of milk powder, because if it was added by dairy farmers, with so many dairy farmers, some add more, some add less, and some conscientious people may not add it. So the melamine content in different batches of milk powder fluctuates greatly, but if it is added during the production of milk powder, due to standard processes and automated equipment, the content of melamine in different batches of milk powder fluctuates very little.

Teach you how to test whether milk powder contains melamine (detailed steps)

Since the safety of milk powder affects the health of children, this is a top priority for parents. I thought of a simple method for everyone, for reference only.

(2) Test whether the milk powder contains melamine:

1. Pour the milk powder into a thicker-than-usual amount with hot water, stir thoroughly until no solid lumps are visible, then put it in the refrigerator and wait for the milk to cool down.

2. Prepare a black cloth and an empty cup. Put a black cloth over the mouth of the empty cup to serve as a filter.

3. Pour the cooled milk over a black cloth and strain.

4. If there is white solid filtered out, rinse it with clean water several times to eliminate other soluble matter.

5. If you find white crystals after rinsing, you can put the crystals into clean water. If the crystals sink to the bottom of the water. Then it is most likely melamine, and this milk powder cannot be used.

This method may not be able to detect trace amounts of melamine, but trace amounts of melamine make the possibility of children getting stones much lower, at least it can be a check.

The above methods are for reference only.

Edit this paragraph to test melamine using professional chemical detection methods

GC-MS method to determine melamine in animal food

Spectra-Quad realizes online detection of melamine content

Ultra-high performance liquid chromatography_electrospray tandem mass spectrometry for determination of residual melamine in feed

Reverse-phase high performance liquid chromatography for determination of melamine content in feed

High-performance liquid chromatography-diode array method for determination of melamine in high-protein foods

High-performance liquid chromatography (HPLC) for determination of melamine in feed

High-performance liquid chromatography-quadrupole Determination of melamine content in feed by rod mass spectrometry combined with solid phase extraction and high performance liquid chromatography for determination of melamine in pet food

Liquid chromatography tandem mass spectrometry (LC-MSMS) analysis Melamine in pet food

Determination of melamine residues in feed by liquid chromatography-tandem mass spectrometry

Determination of melamine in animal food by GC-MS

2.1 Instruments and Conditions

Agilent1100 high performance liquid chromatograph (Agilent Company, USA); diode array detector (DAD), detection wavelength 240nm, column temperature: 40°C.

(1) AgelaVenusilTMASBC18 (4.6×250mm); buffer: 10mM citric acid, 10mM sodium heptanesulfonate; mobile phase: buffer solution: acetonitrile=85:15; flow rate: 1.0mL/min.

(2)