Melamine tainted milk powder Melamine (chemical formula: C3H6N6), commonly known as melamine, protein essence, IUPAC named "1,3,5-triazine-2,4,6-triamino", is a triazine nitrogen-containing heterocyclic organic compounds, used as a chemical raw material. It is used as a chemical raw material. It is a white monoclinic crystal, almost odorless, slightly soluble in water (3.1g/L at room temperature), soluble in methanol, formaldehyde, acetic acid, hot ethylene glycol, glycerol, pyridine, etc., insoluble in acetone, ether, harmful to the body, and cannot be used in food processing or food additives. However, recently, Qinghai, Gansu, Jilin and other provinces reappeared melamine over the standard milk powder, exceeding the standard by more than 500 times. It is likely that the "Sanlu problem milk powder" that has not been completely destroyed is being processed and sold.
Hanyu Pinyin: sān jù qíng àn Melamine (English name: Melamine), is a triazine nitrogen-containing heterocyclic organic compounds, an important nitrogen heterocyclic organic chemical raw materials. Abbreviation: melamine, commonly known as honey amine, protein essence, 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, cyanamide, cyanuronitrilotriamide. Further 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; Molecular modeling
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; molecular structure
Chemical formula (molecular formula) C3H6N6 Relative molecular mass 126.15 CAS Registry Number 108-78-1 EINECS Registry Number 203-615-4 (The picture on the left shows the structure of the molecule. (The left figure is the structure, and the right figure is the schematic diagram of the ball and stick model)
Physical Properties
Melamine is pure white monoclinic crystals, non-combustible, odorless, low toxicity, with a density of 1.573g/cm3 (16℃). Melting point at atmospheric pressure is 354℃, it decomposes when heated sharply; sublimation temperature is 300℃ when heated quickly. Solubility in water increases with temperature, at 20 ℃, about 3.3 g / L, that is, slightly soluble in cold water, soluble in hot water, very slightly soluble in hot ethanol, insoluble in ether, benzene and carbon tetrachloride, soluble in methanol, formaldehyde, acetic acid, hot glycol, glycerol, pyridine and so on.
Edit Chemical Properties
Weakly alkaline (pH=8), with hydrochloric acid, sulfuric acid, nitric acid, acetic acid, oxalic acid and so on can form melamine salt. In neutral or slightly alkaline condition, it can condense with formaldehyde to form various hydroxymethyl melamine, but in slightly acidic condition (pH value 5.5-6.5), it can condense with hydroxymethyl derivatives to form resin products. When hydrolyzed by strong acid or strong alkali aqueous solution, the amine group is gradually replaced by hydroxyl group, and Mr. into a diamide of cyanuric acid, further hydrolyzed to produce a monoamide of cyanuric acid, and finally produce cyanuric acid.
Synthesis process
Melamine was first synthesized by Lippincott in 1834. Early synthesis used the dicyandiamide method: calcium cyanamide (CaCN2) was prepared from calcium carbide (CaC2), and after hydrolysis of the calcium cyanamide, dicyandiamide was generated by dimerization, and then heated to decomposition to prepare melamine. The dicyandiamide method has been eliminated because of the high cost of calcium carbide. Compared with this method, the urea method is less costly and is more commonly used. Using ammonia as the carrier and silica gel as the catalyst, urea is boiled and reacted at a temperature of 380-400°C to first decompose to produce cyanuric acid and further condense to produce melamine. The reaction formula is: 6 CO (NH2)2 → C3N6H6 + 6 NH3 + 3 CO2 The generated melamine gas is cooled and trapped to get the crude product, which is then dissolved, impurities removed and recrystallized to get the finished product. The production of melamine by urea method consumes about 3800kg of urea and 500kg of liquid ammonia per ton of product.
Process classification
According to the different reaction conditions, melamine synthesis process can be divided into high-pressure method (7-10MPa, 370-450 ℃, liquid phase), low-pressure method (0.5-1MPa, 380-440 ℃, liquid phase), and atmospheric pressure method (< ), low-pressure method (0.5-1MPa, 380-440℃, liquid phase) and atmospheric pressure method (< 0.3MPa, 390℃, gas phase). Most of the foreign melamine production process to technology development company name, such as Germany BASF (BASF Process), Austria Linz chemical method (Chemical Linz Process), Lurgi method (Lurgi Process), the United States of America United Signal Chemical Company chemical method (Allied Signal Chemical), Japan's new Nissan process (Nissan Process), the Netherlands Stamicarbon? Both DSM method), etc. These production processes can be basically divided into high-pressure method, low-pressure method and atmospheric pressure method according to different synthesis pressure. At present, the technologically advanced and competitive ones in the world mainly include the high-pressure method of Nissan (Japan) and Allied-Eurotechnica (Italy), the low-pressure method of DSM (Holland) and the atmospheric pressure method of BASF (Germany). China's melamine producers mostly use semi-dry atmospheric pressure method process, the method is to use urea as raw material below 0.1MPa, at about 390 ℃, to synthesize melamine with silica gel as catalyst, and to make melamine crystallize in condenser, the crude product is made into finished product by dissolution, filtration and crystallization.
Edit 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 flame retardant, water reducer, formaldehyde cleaner and so on. The resin has higher hardness than urea-formaldehyde resin, is non-flammable, resistant to water, heat, aging, electric arc, chemical corrosion, good insulating properties, gloss and mechanical strength, and is widely used in wood, plastics, coatings, papermaking, textile, leather, electrical, pharmaceutical and other industries. Its main uses are as follows: (1) decorative panels: can be made into fireproof, shock-resistant, heat-resistant laminates, bright colors, strong heat-resistant decorative panels for aircraft, ships and furniture veneer panels and fireproof, shock-resistant, heat-resistant decorative materials for the house. (2) Coating: etherified with butanol and methanol, it can be used as advanced thermosetting coatings, adhesives for solid powder coatings, metal coatings and decorative paints of high-grade amino resins for vehicles and electrical appliances. (3) Molding powder: after mixing, granulation and other processes can be made into honey amine plastic, non-toxic, stain-resistant, moisture can still maintain good electrical properties, can be made into white, drop-resistant daily utensils, sanitary ware and imitation ceramic tableware, electrical equipment and other high-grade insulating materials. (4) Paper: after etherization with ether, it can be used as paper treatment agent to produce wrinkle-resistant, shrinkage-resistant, non-corrosive banknotes and military maps and other high-grade paper. (5) Melamine formaldehyde dendrimer mixed with other raw materials can also produce fabric finishing agent, leather tanning and wetting agent, varnishing agent and water-resistant agent, rubber adhesive, combustion-aiding agent, high-efficiency cement water-reducing agent, steel desalination agent and so on. (6) Agriculture: In agriculture melamine is used to add in fertilizers.
Edit Consumption Market
The consumption market of melamine in China mainly focuses on wood processing, decorative boards, paints, molded plastics, paper, textile, leather and other industries, among which wood processing industry accounts for 56% of the total domestic consumption. In addition, about 50% of China's melamine is used for export, mainly to Japan, South Korea, Singapore, Spain, Germany, Indonesia, Italy and other countries. The markets with large domestic demand are Guangdong, Guangxi and Southern Jiangsu, with an annual demand of about 12,500 tons. In the two regions, Shandong Haihua Kui Xing Co., Ltd, Sichuan Chuanhua Group Company, Hefei Sifang Group Company's market share of about 65% of the whole market. South Jiangsu market users are mostly individual private enterprises, demand, but the competition is fierce, business risk, followed by the Shanghai market, the annual demand for more than 1.0 million tons, mainly by the Nanjing Jinxing, Petrochemical Industries Company Limited, Sichuan Chuanhua Group Company, Hefei Sifang Group Company. North China market annual demand of about 1.2 million tons, but the region has a large number of manufacturers, price confusion, disorderly competition, so some manufacturers to limit the supply of the region. The market demand in Northeast China, Zhejiang and Fujian, Northwest China, Xianggan and other places is increasing, and the price is relatively stable. With the great development in the western region, the dosage in the future will be increasing, focusing on construction, paint industry, coatings and so on, but due to the poor overall economic level of the region, the demand is not strong. The global consumption of melamine is growing at a rate higher than 5%, but the distribution is not balanced in each region. in 2003, the global demand for melamine was about 1.1 million tons, mainly concentrated in developed countries and regions such as Europe, America and Japan, accounting for 60% to 70% of the global total consumption, mainly used in coatings, decorative paper or laminates, textiles or paper, molded plastics, and adhesives, etc. The global consumption is expected to be about 1.2 million tons in 2004, focusing on construction, paints, adhesives, etc., but the demand is not strong due to the overall economic level of the region. It is expected that the global consumption in 2004 will be about 1.2 million tons, an increase of about 8% over 2003. The consumption of melamine in China has been growing rapidly in recent years, and is currently maintaining a growth rate of 10% to 20%. As the overall development level of China's economy continues to rise, the demand for high-grade building decoration materials is increasing. According to the information from the Flooring Committee of China Timber Circulation Association, the consumption of China's laminate wood flooring market has increased by about 30% year-on-year this year, and the official implementation of the national mandatory standard for controlling the content of free formaldehyde in building materials since July 1, 2002 has also greatly stimulated the consumption of melamine in the production of laminate wood flooring. However, the growth of demand in other areas has been relatively slow. It is expected that the growth of China's consumption of melamine in the next few years will remain at 10% to 20%. [1]
Edit Toxicity Hazards
Currently melamine is considered to be mildly toxic, with an oral LD50 of greater than 3 g/kg body weight in rats. An experiment in 1945 reported that no significant toxicity was observed after feeding large doses of melamine to rats, rabbits and dogs. Prolonged ingestion of melamine by animals can cause reproductive and urinary damage, bladder and kidney stones, and can further induce bladder cancer. 1994 International Manual of Chemical Safety (IMCS) Volume III and International Chemical Safety Card (ICSC), co-edited by the International Organization for Standardization (IOS) of the United Nations International Programme on Chemical Safety (UN/IPCS) and the European Commission (EC), only state that prolonged or repeated ingestion of large quantities of melamine may affect the kidneys and the bladder and result in the production of stones. However, the preliminary findings of the pet food contamination incident in the United States in 2007 concluded that wheat protein powder adulterated with ≤6.6% melamine was the cause of poisoning in pet food, putting a question mark on the above conclusion of mild toxicity. However, for safety reasons, eating utensils made with melamine are usually labeled "not for use in microwave ovens". On September 12, 2008, the Ministry of Health of the People's Republic of China issued the "Diagnosis and Treatment Plan for Urinary Stones in Infants and Young Children Associated with the Consumption of Contaminated Sanlu Infant Formula", which can be referred to by the relevant parties. It is pointed out in the program that most of the stones involve bilateral collecting system and bilateral ureter, which is different from the clinical manifestation of adult urinary stones, and the probability of multiple stones affecting renal function is higher. Since most children do not have the ability to complain of symptoms, parents need to strengthen the observation of the children concerned and rely on abdominal ultrasound and/or CT examination, which can help to determine the diagnosis at an early stage. In terms of treatment, there is no specific antidote for the toxic effects of melamine, and the clinic mainly relies on symptomatic supportive treatment, and surgical intervention can be considered if necessary, to relieve the children from the risk of long-term damage to renal function. Early diagnosis and treatment is the key to early recovery. When melamine enters the body, it undergoes a substitution reaction (hydrolysis) to produce cyanuric acid, which forms a large reticulation with melamine, causing stones. Steven Sandloff, a senior food safety official at the U.S. Food and Drug Administration (FDA), said the study found that only when both melamine and cyanuric acid are present in food products do they pose a threat to the health of infants. It seems that although melamine and cyanuric acid *** only work together to cause kidney stones, melamine is partially hydrolyzed to cyanuric acid in the strongly acidic environment of the stomach, so as long as it is present, it is equivalent to the presence of cyanuric acid, and the danger itself still stems from the melamine.
Edit paragraph human body to melamine tolerance standards
Melamine is a low-toxicity chemical material. The results of animal experiments show that it is metabolized quickly and does not remain in the animal's body, mainly affecting the urinary system. There is a clear dosage-effect relationship between melamine dosage and clinical diseases. The maximum tolerable level of melamine in the body of infants is 15 milligrams per kilogram of milk powder. An expert risk assessment of contaminated infant formula showed that for a 7 kg infant, assuming a daily intake of 150 g of formula, the safe prevalence, i.e. the maximum tolerable level, was 15 mg/kg of formula. The tolerable daily intake (TDI) for melamine is 0.63 mg/kg body weight per day, according to the US Food and Drug Administration (FDA) standard.
Edit Principle of Fake Protein
Due to the flaws in China's method of estimating protein content in the food and feed industry, melamine is also often adulterated by unscrupulous traders into food or feed to enhance the protein content index in food or feed tests, and therefore melamine is also known as "protein essence" by those who fake it. Therefore, melamine is also called "protein essence" by people who cheat. Protein is mainly composed of amino acids. The average nitrogen content of protein is about 16%, while that of melamine is about 66%. The commonly used protein testing method, Kjeldahl method, estimates the protein content by multiplying the measured nitrogen content by 6.25. Therefore, the addition of melamine will make the protein content of food products test falsely high, thus enabling poor quality food and feed to pass the test when the inspection agency only does a simple test of crude protein. It has been estimated that to increase the tested protein content of plant protein powder and feed by one percentage point, the cost of melamine is only 1/5 of the cost of the real protein ingredient. melamine, as a white crystalline powder, has little odor or taste, so it is not easy to be detected after adulteration. Milk powder incident: the protein content of various brands of milk powder is 15-20% (at night in the supermarket to see the packaging is also labeled as 10-20%), the protein in the nitrogen content of an average of 16%. A qualified milk powder protein content of 18% calculated, the nitrogen content of 2.88%. The nitrogen content of melamine is 66.6%, which is 151 times that of fresh milk and 23 times that of milk powder. Adding 0.1g of melamine to every 100g of milk will theoretically increase the protein by 0.625%. Micro-soluble refers to 1g (ml) solute can be dissolved in 100ml to 1000ml solvent, melamine is slightly soluble in water, in milk this kind of water-in-oil emulsion solubility did not find experimental data, it should be better than the solubility of water, to be verified. Testing program: In the existing national standards for milk powder testing, the main tests are protein, fat, bacteria and so on. Melamine is a chemical raw material, which is not allowed to be added to food, so the existing standard will not include the corresponding content. In other words, there is currently no national standard for melamine testing. Therefore, T.V. Rheinland is able to provide authoritative test results for baby food, pet food, feed and its raw materials (including starch, rice protein, corn protein, gluten, grain and oil, etc.) based on the U.S. Food and Chemicals Codex (FCC) quantitative method of HPLC-UV, as well as the HPLC/MS assay (laboratory method). Sanlu milk powder fake protein another explanation for the enterprise to add is urea, and raw milk directly into milk powder is carried out at high temperatures, high temperature makes the urea dehydration reaction, the generation of melamine, so the final output of the milk powder and melamine.
Editing the role of melamine in milk
Milk powder is toxic because it contains melamine, which may be added directly to the milk powder or in the raw milk. Melamine is added to milk and powdered milk mainly because it can be passed off as protein. Foods are tested for protein content as a rule. If there isn't enough protein, it means that the milk has been blended with too much water, and it means that there is too much powder of something else in the milk powder. However, protein is too difficult to detect, biochemists have come up with a lazy way: because protein is nitrogenous, so as long as the nitrogen content of the food is measured, the protein content can be deduced. So milk powder that has had melamine added to it will be very difficult to detect its protein failure, which is the fake protein of melamine.
Edit paragraph pure protein determination
In the face of endless counterfeiting, formal and strict nutritional determination should be milk powder waiting to check the sample of the real protein content, which in developed countries is the determination of the so-called pure protein (or true protein), and was first adopted in China for the food industry's daily standard testing methods. Determination of pure protein in food or feed is also the international standard for testing the nitrogen content of milk (ISO 8968). In fact, it is a modification of the Kjeldahl method, which has been used for many years, including by laboratories in China. The pure protein referred to in this method is also calculated by measuring the nitrogen content of the food x 6.25. This is achieved by separating out the non-protein nitrogen in the sample treatment solution and determining the remaining true protein nitrogen. It is really just one more step: first treat the sample treatment solution with trichloroacetic acid. TCA can make proteins form precipitates, and after filtration, the nitrogen content of the precipitates can be measured separately, so that the real protein content can be known, and the nitrogen content of the fake proteins in the filtrate can also be measured if necessary. If China had changed to this as a standard, food and feed with non-protein melamine and other fake protein will have nothing to hide.
Related cases of illness
In 2007, an outbreak of contaminated pet food occurred in the United States. After the investigation showed that: adulterated ≤ 6.6% melamine wheat protein powder is the cause of pet food poisoning. In 2007, the Shenzhen Inspection and Quarantine Bureau imported 3 batches of "Ai brand" ornamental fish feed from Taiwan, melamine was detected, and the content of melamine was high, respectively 0.35 g/kg, 0.47 g/kg, 0.51 g/kg. These 3 batches of fish feed *** 846 kg. According to the U.S. Food and Drug Administration (FDA) official news, the U.S. FDA for the first time in the U.S. domestic production of feed found to contain melamine, the relevant companies have begun to automatically recall the relevant products. The feed additives containing melamine came from Tembec BTLSR of Toledo, Ohio and Uniscope of Johnstown, Colorado. In September 2008, a contaminated Sanlu infant milk powder incident broke out in China, resulting in kidney stones in infants and children who consumed the contaminated milk powder, which was also attributed to the presence of melamine in the milk powder. The AQSIQ has recently launched an urgent nationwide special inspection of melamine content in infant milk powder. The special inspection was carried out on the remaining 109 enterprises, and 491 batches of products from these enterprises were ****inspected. The results of the stage-by-stage inspection showed that 69 batches of products from 22 infant milk powder manufacturers were detected with different levels of melamine. On September 21, 2008, the Ministry of Health informed the medical treatment situation of the Sanlu brand infant formula incident, pointing out that as of 8:00 p.m. on September 21, 2008, infants and young children who were reported to be hospitalized due to the consumption of infant milk powder were 12,892, of which 104 had serious symptoms; 1,579 had been cured and discharged from hospitals before that. The circular also pointed out that the cumulative number of infants and young children who reported receiving outpatient therapeutic counseling due to consumption of infant formula and who have basically recovered is 39,965. Among all the infants and young children receiving treatment, 81.87% were within 2 years of age, 17.33% were between 2 and 3 years of age, and 0.8% were above 3 years of age. After epidemiological investigation, these infants and young children receiving treatment were basically related to the consumption of Sanlu brand infant formula, and no cases related to the consumption of liquid milk were found. One wave has not yet subsided, but another wave has arisen. Melamine-overloaded milk powder appears again Melamine-poisoned milk powder
The cloud of Hebei Sanlu milk powder has not dissipated, and melamine-overloaded milk powder has reportedly appeared again in Gansu, Qinghai, and Jilin provinces! In Qinghai Province, a dairy factory, from the dairy raw materials detected more than 500 times the melamine exceeded the standard, raw materials from Hebei and other places. Gansu Province Quality Supervision Bureau in the three accept the commissioner to send the milk powder samples, tested melamine exceeded the limited value standard, three samples of melamine content were: 215mg/kg, 1397mg/kg, 323mg/kg, respectively, exceeding the limited value standard 86%, 559%, 130%. At present, the quality supervision department of Qinghai Province has seized this batch of problematic milk powder, about 38 tons, with raw materials from Hebei and other places. The suspects are under control. An internal circular of Qinghai Province reads: On July 3, the public security organs of Haidong area, based on the clues provided by Gansu Province, assisted the quality supervision department to test 64 tons of raw materials and 12 tons of finished products of the problematic milk powder from Dongyuan Dairy Factory in Minhe Hui Tuzi Autonomous County, which were detected to have exceeded the standard of melamine content. A few days before the discovery of the problem milk powder in Gansu and Qinghai, Jilin Province also found that the melamine content of the milk powder seriously exceeded the standard, the public security and industry and commerce departments will be more than 1,000 bags of the problem milk powder was sealed. Jilin Province, the milk powder produced by the relevant enterprises to carry out an inventory and recovery. [2]
Edit melamine detection method
How to detect dairy products at home
1. Press the thicker than usual portion of hot water with powdered milk, stirring thoroughly until no solid blocks, and then put it into the refrigerator, and wait for the milk to cool down. 2. Prepare a black cloth and an empty cup. Put the black cloth over the mouth of the empty cup to act as a strainer. 3. 3. Pour the cooled milk onto the black cloth and strain. 4. If any white solids filter out, rinse several times with water to eliminate other soluble matter. 5. if white crystals are found after rinsing, place the crystals in water. the crystals, if they sink to the bottom of the water. Then it is likely to be melamine, this kind of milk powder can not be used. This method may not be able to find trace amounts of melamine, but trace amounts of melamine make it much less likely that the child will get stones, so at least you can keep a check. The above methods are for reference only.
Professional Chemical Detection Methods
GC-MS Determination of Melamine in Animal Foods Spectra-Quad Enables On-line Detection of Melamine Content Ultra High Performance Liquid Chromatography_Electrospray Tandem Mass Spectrometry (UPLC/ESI-MS) for Determination of Melamine Residues in Feed Reversed-phase HPLC for Determination of Melamine in Feed High-performance Liquid Chromatography with Diode Array Determination Determination of melamine in high protein foodstuffs by high performance liquid chromatography (HPLC) High performance liquid chromatography coupled with quadrupole mass spectrometry High performance liquid chromatography coupled with high performance liquid chromatography for the determination of melamine in pet foodstuffs Melamine in pet foodstuffs by liquid chromatography tandem mass spectrometry (LC-MSMS) Liquid chromatography-tandem mass spectrometry (LC-MSMS) Melamine residue Determination of melamine in animal food by GC-MS 1 Instruments and conditions Agilent1100 high performance liquid chromatograph (USA, Agilent); diode array detector (DAD), detection wavelength 240 nm, column temperature: 40 ℃. (1) AgelaVenusilTMASBC18 (4.6×250 mm); buffer: 10 mM citric acid, 10 mM sodium heptanesulfonate; mobile phase: buffer solution:acetonitrile=85:15; flow rate: 1.0 mL/min. (2) AgelaVenusilTMASBC8 (4.6×250 mm); mobile phase: buffer solution: Acetonitrile=85:15; Buffer: 10 mM citric acid, 10 mM sodium octanesulfonate, adjust pH to 3.0; Flow rate: 1.0 mL/min; Ion-exchange solid-phase extraction column AgelaClearnertTMPCX (Beijing Aijer Technology Co., Ltd.) 2 Reagents and samples Pet feed samples (provided by Feed Supply Center of the Ministry of Agriculture); methanol, acetonitrile for Beijing Aijer Ltd.; ammonia, lead acetate, trichloroacetic acid, were purchased from Beijing Chemical Reagent Company; melamine standard, citric acid, sodium octanesulfonate (Sigma); methanol was chromatographically pure, and the others were chemically pure. 3 Experimental methods 3.1 Sample pretreatment (1) Standard sample preparation: Take 50mg of melamine standard, dissolve and volume to 50mL with 20% methanol to get a standard solution of 1000ppm, and dilute with extraction solution (0.1% trichloroacetic acid) to the desired concentration when using. (2) Extraction: Weigh 5g of feed sample, add 50ml of 0.1% trichloroacetic acid extract, mix thoroughly, add 2mL of 2% lead acetate solution, ultrasonic for 20min. Then take part of the solution and transfer it to 10mL centrifugal tube, centrifuge it at 8000rpm/min for 10min, and take 3mL of supernatant over the mixed cation exchange small column (PCX). (3) Purification (PCX column, 60mg/3mL): a) activation and equilibrium: 3mL methanol, 3mL water b) on the sample: add the extraction solution of 3mL c) rinsing: 3mL water; 3mL methanol; discard the rinsing solution and the column was pumped dry. d) Elution: 5mL 5% ammoniated methanol (v/v) elution. (Preparation of 5% ammoniated methanol: 5mL ammonia + 95mL methanol). e) Concentration: 50°C, nitrogen blow-dry, 20% methanol/water fixed volume to 2mL, HPLC analysis or GC/MS analysis after derivatization. 3.2 HPLC detection method 3.2.1 HPLC-UV detection method for melamine Melamine is a strong polar compound, which is poorly retained on a traditional reversed-phase C18 column, and needs to be chromatographed with ion-pair reagents for good retention and separation. In accordance with the melamine detection method of the U.S. Food and Drug Administration (FDA) and the melamine detection method published by the Chinese Ministry of Agriculture, the method of melamine detection was adopted. Agela ASB series hydrophilic chromatographic columns, good separation results could be obtained, and the analytical chromatograms were as follows: (a) Column: VenusilASBC84.6×250mm; Standard: FDA method; Mobile phase: buffer: acetonitrile=85:15; Buffer: 10mM citric acid, 10mM sodium octanesulfonate, adjusted pH to 3.0; Flow rate: 1.0mL/min; Column temperature: 40oC; Wavelength: 240nm (b) Column: VenusilASB-C184.6×250mm; Standard: Standard Methods of the Ministry of Agriculture of China; Buffer: 10mM citric acid, 10mM sodium heptanesulfonate; Mobile phase: buffer solution: acetonitrile=85:15; Flow rate: 1.0mL/min; Column temperature: 40oC ; Wavelength: 240nm 3.2.2 Melamine LC-MS detection method Because the mobile phase added ion-pair reagent in the HPLC-UV method published by FDA, it limits the use of liquid-quantity coupling method; however, without using the ion-pair reagent chromatographic method, the retention of melamine is very poor in the traditional C18 column, and it can not be separated and quantified in a good way [3]. Based on this problem, Agela developed a new method using Agela ASB series hydrophilic chromatographic columns, which can effectively retain and separate melamine without ion-pair reagents. Therefore, the mobile phase in the method does not contain ion-pairing reagents and can be used for mass spectrometry detection.