Melamine

Not to be confused with Melanin, Melanine, or Melanie.
This article is about the chemical compound. For the chemically-related plastic, see Melamine resin.

Melamine
Structural formula of melamine
Ball-and-stick model of the melamine molecule
Space-filling model of the melamine molecule
Names
Preferred IUPAC name
1,3,5-Triazine-2,4,6-triamine
Other names
2,4,6-Triamino-s-triazine
Cyanurotriamide
Cyanurotriamine
Cyanuramide
Identifiers
3D model (JSmol)
ChEBI
ChemSpider
ECHA InfoCard 100.003.288 Edit this at Wikidata
KEGG
UNII
  • InChI=1S/C3H6N6/c4-1-7-2(5)9-3(6)8-1/h(H6,4,5,6,7,8,9) checkY
    Key: JDSHMPZPIAZGSV-UHFFFAOYSA-N checkY
  • InChI=1/C3H6N6/c4-1-7-2(5)9-3(6)8-1/h(H6,4,5,6,7,8,9)
    Key: JDSHMPZPIAZGSV-UHFFFAOYAF
  • Nc1nc(N)nc(N)n1
Properties
C3H6N6
Molar mass 126.123 g·mol−1
Appearance White solid
Density 1.573 g/cm3[1]
Melting point 343 °C (649 °F; 616 K) (decomposition)[1]
Boiling point Sublimes
3240 mg/ L (20 °C)[2]
Solubility very slightly soluble in hot alcohol[clarification needed], benzene, glycerol, pyridine
insoluble in ether, benzene, CCl4
log P −1.37
Acidity (pKa) 5.0 (conjugated acid)[3]
Basicity (pKb) 9.0 [3]
−61.8·10−6 cm3/mol
1.872[1]
Structure
Monoclinic
Thermochemistry
−1967 kJ/mol
Hazards
> 500 °C (932 °F; 773 K)
Lethal dose or concentration (LD, LC):
3850 mg/kg (rat, oral)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
☒N verify (what is checkY☒N ?)
Marking of product made of Melamine

Melamine /ˈmɛləmiːn/ ⓘ is an organic compound with the formula C3H6N6. This white solid is a trimer of cyanamide, with a 1,3,5-triazine skeleton. Like cyanamide, it contains 66% nitrogen by mass, and its derivatives have fire-retardant properties due to its release of nitrogen gas when burned or charred. Melamine can be combined with formaldehyde and other agents to produce melamine resins. Such resins are characteristically durable thermosetting plastic used in high pressure decorative laminates such as Formica, melamine dinnerware including cooking utensils, plates, plastic products,[4] laminate flooring, and dry erase boards. Melamine foam is used as insulation, soundproofing material and in polymeric cleaning products, such as Magic Eraser.

Melamine-formaldehyde resin tableware was evaluated by the Taiwan Consumers' Foundation to have 20,000 parts per billion of free melamine that could migrate out of the plastic into acidic foods if held at 160 °F (71 °C) for two hours, such as if food were kept heated in contact with it in an oven.[4]

Melamine gained infamy because Chinese food producers added it to baby formula in order to increase the apparent protein content.[5][6] Ingestion of melamine may lead to reproductive damage, or bladder or kidney stones, and bladder cancer. It is also an irritant when inhaled or in contact with the skin or eyes. The United Nations' food standards body, the Codex Alimentarius Commission, has set the maximum amount of melamine allowed in powdered infant formula to 1 mg/kg and the amount of the chemical allowed in other foods and animal feed to 2.5 mg/kg. While not legally binding, the levels allow countries to ban importation of products with excessive levels of melamine.

Etymology

The German word Melamin was coined by combining the words melam (a derivative of ammonium thiocyanate) and amine.[7][8] Melamine is, therefore, unrelated etymologically to the root melas (μέλας, meaning 'black' in Greek), from which the words melanin, a pigment, and melatonin, a hormone, are formed.

Uses

Plastics and building materials

In one large-scale application, melamine is combined with formaldehyde and other agents to produce melamine resins. Such resins are characteristically durable thermosetting plastic used in high-pressure decorative laminates such as Wilsonart, melamine dinnerware, laminate flooring, and dry erase boards.[9] Melamine cookware is not microwave-safe,[10] and can be identified from the fact it is "slightly heavier and noticeably thicker than its plastic counterparts."[11]

Melamine foam is used as insulation, soundproofing material and in polymeric cleaning products, such as Magic Eraser.

Melamine is one of the major components in Pigment Yellow 150, a colorant in inks and plastics.

Melamine also is used in the fabrication of melamine polysulfonate, used as a superplasticizer for making high-resistance concrete. Sulfonated melamine formaldehyde (SMF) is a polymer used as a cement admixture to reduce the water content in concrete while increasing the fluidity and the workability of the mix during handling and pouring. It results in concrete with a lower porosity and a higher mechanical strength, exhibiting an improved resistance to aggressive environments and a longer lifetime.

Fertilizers

Melamine was once envisioned as fertilizer for crops during the 1950s and 1960s because of its high (66% by mass) nitrogen content.[12] However, melamine is much more expensive to produce than other common nitrogen fertilizers, such as urea. The mineralization (degradation to ammonia) for melamine is slow, making this product both economically and scientifically impractical for use as a fertilizer.[citation needed]

Melamine dinnerware

Fire-retardant additives

Melamine and its salts are used as fire-retardant additives in paints, plastics, and paper.[13] A melamine fiber, Basofil, has low thermal conductivity, excellent flame resistance and is self-extinguishing; this makes it useful for flame-resistant protective clothing, either alone or as a blend with other fibres.[14]

Food additive

Melamine is sometimes illegally added to food products in order to increase the apparent protein content. Standard tests, such as the Kjeldahl and Dumas tests, estimate protein levels by measuring the nitrogen content, so they can be misled by the addition of nitrogen-rich, but non-proteinaceous compounds such as melamine. There are instruments available today that can differentiate melamine nitrogen from protein nitrogen.[15]

Medicine

Melamine derivatives of arsenical drugs are potentially important in the treatment of African trypanosomiasis.[16]

Melamine use as non-protein nitrogen (NPN) for cattle was described in a 1958 patent.[17] In 1978, however, a study concluded that melamine "may not be an acceptable non-protein N source for ruminants" because its hydrolysis in cattle is slower and less complete than other nitrogen sources such as cottonseed meal and urea.[18]

Toxicity

The short-term lethal dose of melamine is on a par with common table salt, with an LD50 of more than 3 grams per kilogram of bodyweight.[19] U.S. Food and Drug Administration (FDA) scientists explained that when melamine and cyanuric acid are absorbed into the bloodstream, they concentrate and interact in the urine-filled renal tubules, then crystallize and form large numbers of round, yellow crystals, which in turn block and damage the renal cells that line the tubes, causing the kidneys to malfunction[20] and lead to kidney stones, kidney failure, and death.[21] Signs of melamine toxicity can include irritability, blood in the urine, little to no urine, symptoms of kidney infection, or high blood pressure.[22]

The European Union set a standard for acceptable human consumption (tolerable daily intake or TDI) of melamine at 0.2 mg per kilogram of body mass[23] (previously 0.5 mg/kg), Canada declared a limit of 0.35 mg/kg, and the US FDA's limit was put at 0.063 mg/kg (previously 0.63 mg/kg). The World Health Organization's food safety director estimated that the amount of melamine a person could stand per day without incurring a bigger health risk, the TDI, was 0.2 mg per kilogram of body mass.[24]

Toxicity of melamine can be mediated by intestinal microbiota. In culture, Raoultella terrigena, which rarely colonizes mammalian intestines,[25] was shown to convert melamine to cyanuric acid directly. Rats colonized by R. terrigena showed greater melamine-induced kidney damage compared to those not colonized.[26]

Acute toxicity

Melamine is reported to have an oral median lethal dose (LD50) of 3248 mg/kg based on rat data. It is also an irritant when inhaled or in contact with the skin or eyes. The reported dermal LD50 is greater than 1000 mg/kg for rabbits. A study by Soviet researchers in the 1980s suggested that melamine cyanurate, commonly used as a fire retardant,[27] could be more toxic than either melamine or cyanuric acid alone.[28] For rats and mice, the reported LD50 for melamine cyanurate was 4.1 g/kg (given inside the stomach) and 3.5 g/kg (via inhalation), compared to 6.0 and 4.3 g/kg for melamine and 7.7 and 3.4 g/kg for cyanuric acid respectively.

A toxicology study in animals conducted after recalls of contaminated pet food concluded that the combination of melamine and cyanuric acid in diet does lead to acute kidney injury in cats.[29] A 2008 study produced similar experimental results in rats and characterized the melamine and cyanuric acid in contaminated pet food from the 2007 outbreak.[30] A 2010 study from Lanzhou University attributed kidney failure in humans to uric acid stone accumulation after ingestion of melamine resulting in a rapid aggregation of metabolites such as cyanuric acid diamide (ammeline) and cyanuric acid.[31] A 2013 study demonstrated that melamine can be metabolized to cyanuric acid by gut bacteria. In particular, Klebsiella terrigena was determined to be a factor in melamine toxicity. In culture, K. terrigena was shown to convert melamine to cyanuric acid directly. Cyanuric acid was detected in the kidneys of rats administered melamine alone, and the concentration after Klebsiella colonization was increased.[26]

Chronic toxicity

Ingestion of melamine may lead to reproductive damage, or bladder or kidney stones, which can lead to bladder cancer.[32][33][34][35]

A study in 1953 reported that dogs fed 3% melamine for a year had the following changes in their urine: (1) reduced specific gravity, (2) increased output, (3) melamine crystalluria, and (4) protein and occult blood.[36]

A survey commissioned by the American Association of Veterinary Laboratory Diagnosticians suggested that crystals formed in the kidneys when melamine combined with cyanuric acid, "don't dissolve easily. They go away slowly, if at all, so there is the potential for chronic toxicity."[37][38][39]

Metabolism

Melamine is a metabolite of cyromazine, a pesticide.[40] It has been reported that cyromazine can also be converted to melamine in plants.[41][42]

Treatment of urolithiasis

Fast diagnosis and treatment of acute obstructive urolithiasis may prevent the development of acute kidney failure. Urine alkalinization and stone liberalization have been reported to be the most effective treatments in humans.[31]

Regulation in food and feed

The United Nations' food standards body, Codex Alimentarius Commission, has set the maximum amount of melamine allowed in powdered infant formula to 1 mg/kg and the amount of the chemical allowed in other foods and animal feed to 2.5 mg/kg. While not legally binding, the levels allow countries to ban importation of products with excessive levels of melamine.[43]

Synthesis and reactions

Melamine was first synthesized by the German chemist Justus von Liebig in 1834. In early production, first calcium cyanamide was converted into dicyandiamide, which was heated above its melting temperature to produce melamine. Today most industrial manufacturers use urea in the following reaction to produce melamine:

6 (NH2)2CO → C3H6N6 + 6 NH3 + 3 CO2

In the first step, urea decomposes into cyanic acid and ammonia:

(NH2)2CO → HNCO + NH3

Cyanic acid polymerizes to cyanuric acid, which condenses with the liberated ammonia forming melamine. The released water reacts with cyanic acid, which helps to drive the reaction:

6 HNCO + 3 NH3 → C3H6N6 + 3 CO2 + 3NH3

The above reaction can be carried out by either of two methods: catalyzed gas-phase production or high pressure liquid-phase production. In one method, molten urea is introduced onto a fluidized bed with catalyst for reaction. Hot ammonia gas is also present to fluidize the bed and inhibit deammonization. The effluent then is cooled. Ammonia and carbon dioxide in the off-gas are separated from the melamine-containing slurry. The slurry is further concentrated and crystallized to yield melamine.[44] Major manufacturers and licensors such as Orascom Construction Industries, BASF, and Eurotecnica have developed some proprietary methods.

The off-gas contains large amounts of ammonia. Therefore, melamine production is often integrated into urea production, which uses ammonia as feedstock.

Crystallization and washing of melamine generates a considerable amount of waste water, which may be concentrated into a solid (1.5–5% of the weight) for easier disposal. The solid may contain approximately 70% melamine, 23% oxytriazines (ammeline, ammelide, and cyanuric acid), 0.7% polycondensates (melem, melam, and melon).[45] In the Eurotecnica process, however, there is no solid waste and the contaminants are decomposed to ammonia and carbon dioxide and sent as off gas to the upstream urea plant; accordingly, the waste water can be recycled to the melamine plant itself or used as clean cooling water make-up.[46]

Melamine reacts with acid and related compounds to form melamine cyanurate and related crystal structures, which have been implicated as contaminants or biomarkers in Chinese protein adulterations.

Drug derivatives

Melamine is part of the core structure for a number of drugs including almitrine, altretamine, cyromazine, ethylhexyl triazone, iscotrizinol, meladrazine, melarsomine, melarsoprol, tretamine, trinitrotriazine, and others.[47]

Production in mainland China

Between the late 1990s and early 2000s, both consumption and production of melamine grew considerably in mainland China. By early 2006, melamine production in mainland China is reported to be in "serious surplus".[48] Between 2002 and 2007, while the global melamine price remained stable, a steep increase in the price of urea (feedstock for melamine) has reduced the profitability of melamine manufacturing. Currently, China is the world's largest exporter of melamine, while its domestic consumption still grows by 10% per year. However, reduced profit has already caused other joint melamine ventures to be postponed there.

Surplus melamine has been an adulterant for feedstock and milk in mainland China for several years now because it can make diluted or poor quality material appear to be higher in protein content by elevating the total nitrogen content detected by some simple protein tests. Actions taken in 2008 by the Government of China have reduced the practice of adulteration, with the goal of eliminating it. As a result of the Chinese milk scandal, court trials began in December 2008 for six people involved in adding melamine in food products, ending in January 2009 with two of the convicts being sentenced to death and executed.[49][50]

Melamine poisoning by tainted food

Melamine has been involved in several food recalls after the discovery of severe kidney damage to children and pets poisoned by melamine-adulterated food.

2007 animal-feed recalls

Further information: 2007 pet food recalls and Chinese protein adulteration

In 2007, a pet food recall was initiated by Menu Foods and other pet food manufacturers who had found their products had been contaminated and caused serious illnesses or deaths in some of the animals that had eaten them.[51][52][53] In March 2007, the US Food and Drug Administration reported finding white granular melamine in the pet food, in samples of white granular wheat gluten imported from a single source in China, Xuzhou Anying Biologic Technology[54] as well as in crystalline form in the kidneys and in urine of affected animals.[55] Further vegetable protein imported from China was later implicated.

In April 2007, The New York Times reported that the addition of "melamine scrap" into fish and livestock feed to give the false appearance of a higher level of protein was an "open secret" in many parts of mainland China, reporting that this melamine scrap was being produced by at least one plant processing coal into melamine.[56] Four days later, the New York Times reported that, despite the widely reported ban on melamine use in vegetable proteins in mainland China, at least some chemical manufacturers continued to report selling it for use in animal feed and in products for human consumption. Li Xiuping, a manager at Henan Xinxiang Huaxing Chemical in Henan Province, stated, "Our chemical products are mostly used for additives, not for animal feed. Melamine is mainly used in the chemical industry, but it can also be used in making cakes."[57] Shandong Mingshui Great Chemical Group, the company reported by the New York Times as producing melamine from coal, produces and sells both urea and melamine but does not list melamine resin as a product.[58]

Another recall incident in 2007 involved melamine which had been purposely added as a binder to fish and livestock feed manufactured in the United States. This was traced to suppliers in Ohio and Colorado.[59]

2008 Chinese outbreak

Further information: 2008 Chinese milk scandal

In September 2008, several companies, including Nestlé, were implicated in a scandal involving milk and infant formula which had been adulterated with melamine, leading to kidney stones and other kidney failure, especially among young children. By December 2008, nearly 300,000 people had become ill, with more than 50,000 infant hospitalizations and six infant deaths.[60][61][62] In a study published in the New England Journal of Medicine, it was reported that melamine exposure increased the incidence of urinary tract stones by seven times in children.[63] Melamine may have been added to fool government protein content tests after water was added to fraudulently dilute the milk. Because of melamine's high nitrogen content (66% by mass versus approximately 10–12% for typical protein), it can cause the protein content of food to appear higher than the true value.[64][65] Officials estimate that about 20% of the dairy companies tested in China sell products tainted with melamine.[66] On January 22, 2009, three of those involved in the scandal (including one conditional sentence) were sentenced to death in a Chinese court.[citation needed]

In October 2008, "Select Fresh Brown Eggs" exported to Hong Kong from the Hanwei Group in Dalian in northeastern China were found to be contaminated with nearly twice the legal limit of melamine. York Chow, the health secretary of Hong Kong, said he thought animal feeds might be the source of the contamination and announced that the Hong Kong Centre for Food Safety would henceforward be testing all mainland Chinese pork, farmed fish, animal feed, chicken meat, eggs, and offal products for melamine.[67]

As of July 2010, Chinese authorities were still reporting some seizures of melamine-contaminated dairy product in some provinces, though it was unclear whether these new contaminations constituted wholly new adulterations or were the result of illegal reuse of material from the 2008 adulterations.[68][69]

On characterization and treatment of urinary stones in affected infants, The New England Journal of Medicine printed an editorial in March 2009, along with reports on cases from Beijing, Hong Kong and Taipei.[70]

Urinary calculi specimens were collected from 15 cases treated in Beijing and were analyzed as unknown objects for their components at Beijing Institute of Microchemistry using infrared spectroscopy, nuclear magnetic resonance, and high performance liquid chromatography. The result of the analysis showed that the calculus was composed of melamine and uric acid, and the molecular ratio of uric acid to melamine was around 2:1.[71]

In a 2009 study of 683 children diagnosed in Beijing in 2008 with nephrolithiasis and 6,498 children without nephrolithiasis aged < 3 years, investigators found that in children exposed to melamine levels < 0.2 mg/kg per day, the risk for nephrolithiasis was 1.7 times higher than in those without melamine exposure, suggesting that the risk of melamine-induced nephrolithiasis in young children starts at a lower intake level than the levels recommended by the World Health Organization.[72]

In a study published in 2010, researchers from Beijing University studying ultrasound images of infants who fell ill in the 2008 contamination found that while most children in a rural Chinese area recovered, 12 per cent still showed kidney abnormalities six months later. "The potential for long-term complications after exposure to melamine remains a serious concern," the report said. "Our results suggest a need for further follow-up of affected children to evaluate the possible long-term impact on health, including renal function."[73] Another 2010 follow-up study from Lanzhou University attributed the uric acid stone accumulation after ingestion of melamine to a rapid aggradation of metabolites such as cyanuric acid diamide (ammeline) and cyanuric acid and reported that urine alkalinization and stone liberalization were the most effective treatments.[31]

Until the 2007 pet food recalls, melamine had not routinely been monitored in food, except in the context of plastic safety or insecticide residue.

Following the deaths of children in China from powdered milk in 2008, the Joint Research Centre (JRC) of the European Commission in Belgium set up a website about methods to detect melamine.[74] In May 2009, the JRC published the results of a study that benchmarked the ability of labs around the world to accurately measure melamine in food. The study concluded that the majority of labs can effectively detect melamine in food.[75]

In October 2008, the U.S. Food and Drug Administration (FDA) issued new methods for the analysis of melamine and cyanuric acid in infant formulations in the Laboratory Information Bulletin No 4421.[76] Similar recommendations have been issued by other authorities, like the Japanese Ministry of Health, Labor and Welfare,[77] both based on liquid chromatography – mass spectrometry (LC/MS) detection after hydrophilic interaction liquid chromatography (HILIC) separation.[78]

The existing methods for melamine determination using a triple quadrupole liquid chromatography – mass spectrometry (LC/MS) after solid phase extraction (SPE) are often complex and time-consuming. However, electrospray ionization methods coupled with mass spectrometry allow a rapid and direct analysis of samples with complex matrices: the native liquid samples are directly ionized under ambient conditions in their original solution. In December 2008, two new fast and inexpensive methods for detecting melamine in liquids have been published.[79]

Ultrasound-assisted extractive electrospray ionization mass spectrometry (EESI-MS) has been developed at ETH Zurich (Switzerland) by Zhu, Chingin et al., (2008)[80] for a rapid detection of melamine in untreated food samples. Ultrasounds are used to nebulize the melamine-containing liquids into a fine spray. The spray is then ionised by extractive electrospray ionisation (EESI) and analysed using tandem mass spectrometry (MS/MS). An analysis requires 30 seconds per sample. The limit of detection of melamine is a few nanograms of melamine per gram of milk.[81]

Huang et al. (2008) have also developed at Purdue University (US) a simpler instrumentation and a faster method by using a low-temperature plasma probe to ionize the samples. The major obstacles being solved, the ESI-MS technique allows now high-throughput analysis of melamine traces in complex mixtures.[82]

The Melaminometer[83][84][85] was a hypothetical design for a synthetic biology circuit, to be used for detecting melamine and related chemical analogues such as cyanuric acid. The conceptual project is hosted at OpenWetWare as open source biology in collaboration with DIYbio and has been discussed in various newspapers in the context of homebrew biotechnology. As of October 2009, the design has not been verified.

Because melamine resin is often used in food packaging and tableware, melamine at ppm level (1 part per million) in food and beverage has been reported due to migration from melamine-containing resins.[86] Small amounts of melamine have also been reported in foodstuff as a metabolite product of cyromazine, an insecticide used on animals and crops.[87]

The Food Safety and Inspection Service (FSIS) of the United States Department of Agriculture (USDA) provides a test method for analyzing cyromazine and melamine in animal tissues.[88][89] In 2007, the FDA began using a high performance liquid chromatography test to determine the melamine, ammeline, ammelide, and cyanuric acid contamination in food.[90] Another procedure is based on surface-enhanced Raman spectroscopy (SERS).[91][92]

Member states of the European Union are required under Commission Decision 2008/757/EC[93] to ensure that all composite products containing at least 15% of milk product, originating from China, are systematically tested before import into the Community and that all such products which are shown to contain melamine in excess of 2.5 mg/kg are immediately destroyed.

Detection in biological specimens

The presence of melamine in urine specimens from children who consumed adulterated milk products has been determined by liquid chromatography-mass spectrometry.[94]

Melamine on metal surfaces

It is reported that melamine molecules adsorbed on gold[95] or silver[96] surface tend to arrange into honeycomb or closed-packed structures. Such a self-assembly occurs due to the inter-molecular hydrogen bond interaction. This ordering was further investigated using classical Monte Carlo[97] and DFT[98] methods.

See also

References

  1. ^ a b c Haynes, William M., ed. (2011). CRC Handbook of Chemistry and Physics (92nd ed.). CRC Press. p. 3.516. ISBN 978-1439855119.
  2. ^ Melamine from PubChem
  3. ^ a b Jang, Y.H., Hwang, S., Chang, S.B., Ku, J. and Chung, D.S. (2009). "Acid Dissociation Constants of Melamine Derivatives from Density Functional Theory Calculations". The Journal of Physical Chemistry A. 113 (46): 13036–13040. Bibcode:2009JPCA..11313036J. doi:10.1021/jp9053583. PMID 19845385.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  4. ^ a b Nutrition, Center for Food Safety and Applied (December 19, 2022). "Melamine in Tableware Questions and Answers". FDA.
  5. ^ Hau, Anthony Kai-Ching; Kwan, Tze Hoi; Li, Philip Kam-tao (2009). "Melamine Toxicity and the Kidney". Journal of the American Society of Nephrology. 20 (2): 245–250. doi:10.1681/asn.2008101065. PMID 19193777.
  6. ^ Scholl, Peter F.; Bergana, Marti Mamula; Yakes, Betsy Jean; Xie, Zhuohong; Zbylut, Steven; Downey, Gerard; Mossoba, Magdi; Jablonski, Joseph; Magaletta, Robert; Holroyd, Stephen E.; Buehler, Martin (July 19, 2017). "Effects of the Adulteration Technique on the Near-Infrared Detection of Melamine in Milk Powder". Journal of Agricultural and Food Chemistry. 65 (28): 5799–5809. doi:10.1021/acs.jafc.7b02083. ISSN 0021-8561. PMID 28617599.
  7. ^ "Melamine". The American Heritage Dictionary of the English Language (Fourth ed.). 2000. Archived from the original on December 1, 2008. Retrieved September 28, 2008.
  8. ^ Bann, Bernard; Miller, Samuel A. (1958). "Melamines and derivatives of melamine". Chemical Reviews. 58: 131–172. doi:10.1021/cr50019a004.
  9. ^ Deim, H.; Matthias, G.; Wagner, R. A. (2012). "Amino Resins". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a02_115.pub2. ISBN 978-3527306732.
  10. ^ "Melamine in Tableware Questions and Answers". United States: Food and Drug Administration. December 19, 2022. Retrieved December 21, 2022. Foods and drinks should not be heated on melamine-based dinnerware in microwave ovens.
  11. ^ https://www.bzyoo.com/blogs/news/how-can-you-identify-melamine-dishes
  12. ^ Hauck, R. D.; Stephenson, H. F. (1964). "Fertilizer Nitrogen Sources, Nitrification of Triazine Nitrogen". Journal of Agricultural and Food Chemistry. 12 (2): 147–151. doi:10.1021/jf60132a014.
  13. ^ Ashford, Robert D. (2011) Ashford's Dictionary of Industrial Chemicals, 3rd ed. Wavelength. p. 5713. ISBN 9780952267430.
  14. ^ "Melamine Fibres". Polymer Properties Database.
  15. ^ Moore, Jeffrey C.; Devries, Jonathan W.; Lipp, Markus; Griffiths, James C.; Abernethy, Darrell R. (2010). "Total Protein Methods and Their Potential Utility to Reduce the Risk of Food Protein Adulteration". Comprehensive Reviews in Food Science and Food Safety. 9 (4): 330–357. doi:10.1111/j.1541-4337.2010.00114.x. PMID 33467839.
  16. ^ Barrett, Michael P.; Gilbert, Ian H. (2006). "Targeting of Toxic Compounds to the Trypanosome's Interior". Advances in Parasitology. Vol. 63. pp. 125–183. doi:10.1016/S0065-308X(06)63002-9. ISBN 9780120317639. PMID 17134653.
  17. ^ Colby, Robert W. and Mesler, Robert J. Jr. (1958) "Ruminant feed compositions". U.S. patent 2,819,968.
  18. ^ Newton, G. L.; Utley, P. R. (1978). "Melamine as a Dietary Nitrogen Source for Ruminants". Journal of Animal Science. 47 (6): 1338–1344. doi:10.2527/jas1978.4761338x.
  19. ^ "Melamine in milk by David Bradley". Sciencebase. September 17, 2008. Retrieved September 27, 2008.
  20. ^ Weise, Elizabeth (August 5, 2007). "Poison pet food woes seem to hit cats harder". USA Today. Retrieved October 1, 2008.
  21. ^ Nutrition, Center for Food Safety and Applied (December 19, 2022). "Melamine in Tableware Questions and Answers". FDA.
  22. ^ Nutrition, Center for Food Safety and Applied (December 19, 2022). "Melamine in Tableware Questions and Answers". FDA.
  23. ^ Harrington, Rory (April 15, 2010). "EFSA cuts melamine TDI by 60 per cent". FoodQualityNews.com. Retrieved April 16, 2010.
  24. ^ Endreszl, Lara (December 10, 2008). "Safe Melamine Levels Named by World Health Organization". Health News. Archived from the original on March 18, 2009.
  25. ^ Neergaard, Lauran (February 14, 2013). "Study Examines Why Most Survived China's Melamine Scare". Food Manufacturing News. Food Manufacturing. Retrieved February 22, 2013.
  26. ^ a b Zheng, X.; et al. (2013). "Melamine-induced renal toxicity is mediated by the gut microbiota". Science Translational Medicine. 5 (172): 172ra22. doi:10.1126/scitranslmed.3005114. PMID 23408055. S2CID 23408614.
  27. ^ "Flame Retardants Center: Melamine Compounds". Specialchem4polymers.com. April 19, 2010. Archived from the original on September 22, 2008. Retrieved June 20, 2012.
  28. ^ Babayan, A. A. and Aleksandryan, A. V. (1985). "Токсичные характеристики цианурата меламина, меламина и циануровой кислоты" [Toxicological characteristics of melamine cyanurate, melamine and cyanuric acid]. Zhurnal Eksperimental'noi I Klinicheskoi Meditsiny. 25: 345–249.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  29. ^ Puschner, B.; Poppenga, R. H.; Lowenstine, L. J.; Filigenzi, M. S.; Pesavento, P. A. (2007). "Assessment of Melamine and Cyanuric Acid Toxicity in Cats". Journal of Veterinary Diagnostic Investigation. 19 (6): 616–24. doi:10.1177/104063870701900602. PMID 17998549.
  30. ^ Dobson, R. L. M.; Motlagh, S.; Quijano, M.; Cambron, R. T.; Baker, T. R.; Pullen, A. M.; Regg, B. T.; Bigalow-Kern, A. S.; Vennard, T.; Fix, A.; Reimschuessel, R.; Overmann, G.; Shan, Y.; Daston, G. P. (2008). "Identification and Characterization of Toxicity of Contaminants in Pet Food Leading to an Outbreak of Renal Toxicity in Cats and Dogs". Toxicological Sciences. 106 (1): 251–262. doi:10.1093/toxsci/kfn160. PMID 18689873.
  31. ^ a b c Zhang, Xiangbo; Bai, Jinliang; Ma, Pengcheng; Ma, Jianhua; Wan, Jianghou; Jiang, Bin (2010). "Melamine-induced infant urinary calculi: A report on 24 cases and a 1-year follow-up". Urological Research. 38 (5): 391–5. doi:10.1007/s00240-010-0279-0. PMID 20517603. S2CID 23832448.
  32. ^ "International Chemical Safety Card". Cdc.gov. Archived from the original on June 5, 2012. Retrieved June 20, 2012.
  33. ^ OSHA – Chemical sampling information
  34. ^ WHO – Some Chemicals that Cause Tumors of the Kidney or Urinary Bladder in Rodents and Some Other Substances[page needed]
  35. ^ Heck, Henry d'A.; Tyl, Rochelle W. (1985). "The induction of bladder stones by terephthalic acid, dimethyl terephthalate, and melamine (2,4,6-triamino-s-triazine) and its relevance to risk assessment". Regulatory Toxicology and Pharmacology. 5 (3): 294–313. doi:10.1016/0273-2300(85)90044-3. PMID 3903881.
  36. ^ Tusing, T.W. "Chronic Feeding – Dogs", cited by "Summary of toxicity data – trichloromelamine" by California Environmental Protection Agency, last revised on February 4, 2002, URL Archived June 25, 2007, at the Wayback Machine Retrieved September 5, 2007
  37. ^ "Culprit in pet food deaths may be combination of contaminants". Michigan State University. November 29, 2007. Retrieved December 7, 2007.
  38. ^ "Proceedings of the American Association of Veterinarian Laboratory Diagnosticians 50th Annual Conference" (PDF). AAVLD. October 2007. Archived from the original (PDF) on September 20, 2018. Retrieved May 16, 2021.
  39. ^ "Researchers examine contaminants in food, deaths of pets". AVMA. November 2007. Archived from the original on November 22, 2007. Retrieved November 30, 2007.
  40. ^ "Cyromazine" (PDF). European Medicines Agency. January 2001. Archived from the original (PDF) on October 10, 2008. Retrieved June 20, 2012.
  41. ^ Lim, Lori O.; Scherer, Susan J.; Shuler, Kenneth D.; Toth, John P. (1990). "Disposition of cyromazine in plants under environmental conditions". Journal of Agricultural and Food Chemistry. 38 (3): 860–864. doi:10.1021/jf00093a057.
  42. ^ "Cyromazine" (PDF). Pesticide Residues in Food, 1992 Evaluations: Residues. Food & Agriculture Org. 1993. pp. 265–. ISBN 978-92-5-103341-8. Archived from the original (PDF) on October 21, 2012.
  43. ^ "International experts limit melamine levels in food". World Health Organization. July 6, 2010. Archived from the original on July 7, 2010. Retrieved July 7, 2010. Establishment of maximum levels will help governments differentiate between low levels of unavoidable melamine occurrence that do not cause health problems, and deliberate adulteration – thereby protecting public health without unnecessary impediments to international trade.
  44. ^ Kirk-Othmer (1978). Kirk-Othmer encyclopedia of chemical technology. Vol. 7 (3rd ed.). pp. 303–304. ISBN 9780471485162.
  45. ^ Lahalih, Shawqui M.; Absi-Halabi, M. (1989). "Recovery of solids from melamine waste effluents and their conversion to useful products". Industrial & Engineering Chemistry Research. 28 (4): 500–504. doi:10.1021/ie00088a020.
  46. ^ "How a golden chemical became greeneer", Nitrogen+Syngas, Issue 293, May–June 2008.
  47. ^ Matsui, Kohji (1972). "Syntheses and Reactions of s-Triazine Derivatives". Journal of Synthetic Organic Chemistry, Japan (in Japanese). 30 (1): 19–35. doi:10.5059/yukigoseikyokaishi.30.19. ISSN 0037-9980.
  48. ^ Ruilin, Wang (January 6, 2006). "Melamine capacity is serious surplus". China Chemical Reporter. Retrieved April 21, 2007.
  49. ^ "Tainted milk trial opens in China". BBC. December 26, 2008. Retrieved January 7, 2009.
  50. ^ "Chinese Milk Scam Duo Face Death". BBC. January 22, 2009. Retrieved January 22, 2009.
  51. ^ Dry food added to pet food recall list. CNN. March 30, 2007
  52. ^ "Pet food recall". AVMA. April 11, 2007. Archived from the original on April 15, 2007. Retrieved June 20, 2012.
  53. ^ Press release by Natural Balance Pet Foods Archived May 11, 2012, at the Wayback Machine
  54. ^ Melamine Pet Food Recall – Frequently Asked Questions. FDA.gov (Updated October 7, 2009)
  55. ^ "FDA: Pet food recall". Fda.gov. Retrieved June 20, 2012.
  56. ^ Barboza, David; Barrionuevo, Alexei (April 30, 2007). "Filler in Animal Feed Is Open Secret in China". The New York Times. Retrieved April 30, 2007.
  57. ^ Barboza, David & Barrionuevo, Alexei (May 3, 2007). "China Makes Arrest in Pet Food Case". The New York Times. Retrieved May 3, 2007.
  58. ^ "Products". Shandong Mingshui Great Chemical Group. Archived from the original on July 26, 2005. Retrieved April 30, 2007.
  59. ^ Martin, Andrew (May 31, 2007). "Poison used in China is found in U.S.-made animal feed". The New York Times. Retrieved June 1, 2007.
  60. ^ Scott McDonald (September 21, 2008). "Nearly 53,000 Chinese children sick from milk". The Pantagraph. ISSN 2641-7634. Archived from the original on May 16, 2021. Retrieved May 16, 2021.
  61. ^ Jane Macartney, China baby milk scandal spreads as sick toll rises to 13,000[dead link‍], The Times (September 22, 2008)
  62. ^ "Toxicological and Health Aspects of Melamine and Cyanuric Acid" (PDF). WHO. 2009. Retrieved August 13, 2009.
  63. ^ Guan, Na; Fan, Qingfeng; Ding, Jie; Zhao, Yiming; Lu, Jingqiao; Ai, Yi; Xu, Guobin; Zhu, Sainan; Yao, Chen; Jiang, Lina; Miao, Jing; Zhang, Han; Zhao, Dan; Liu, Xiaoyu; Yao, Yong (2009). "Melamine-Contaminated Powdered Formula and Urolithiasis in Young Children". New England Journal of Medicine. 360 (11): 1067–74. doi:10.1056/NEJMoa0809550. PMID 19196669.
  64. ^ "Fonterra says somebody sabotaged milk". NZ Herald. September 15, 2008. Retrieved September 22, 2008.
  65. ^ "Toxic milk toll rockets in China". BBC News. September 15, 2008. Retrieved September 22, 2008.
  66. ^ Tran, Tini (September 17, 2008). "6,200 Chinese babies ill, 3 die from tainted milk". Yahoo! News. Archived from the original on September 21, 2008. Retrieved September 22, 2008.
  67. ^ "Hong Kong widens China food tests". BBC News. October 27, 2008. Retrieved October 27, 2008.
  68. ^ "Melamine tainted milk re-emerges in northwest China plant". Xinhua. July 9, 2010. Archived from the original on July 11, 2010. Retrieved July 9, 2010.
  69. ^ Wines, Michael (July 9, 2010). "Tainted Dairy Products Seized in Western China". New York Times. Retrieved July 9, 2010.
  70. ^ Langman, Craig B. (2009). "Melamine, Powdered Milk, and Nephrolithiasis in Chinese Infants". The New England Journal of Medicine. 360 (11): 1139–41. doi:10.1056/NEJMe0900361. PMID 19196666.
  71. ^ Sun, N.; Shen, Y.; Sun, Q.; Li, X. R.; Jia, L. Q.; Zhang, G. J.; Zhang, W. P.; Chen, Z.; Fan, J. F.; Jiang, Y. P.; Feng, D. C.; Zhang, R. F.; Zhu, X. Y.; Xiao, H. Z. (2009). "Diagnosis and treatment of melamine-associated urinary calculus complicated with acute renal failure in infants and young children". Chinese Medical Journal. 122 (3): 245–51. PMID 19236798.
  72. ^ Li, Gang; Jiao, Shufang; Yin, Xiangjun; Deng, Ying; Pang, Xinghuo; Wang, Yan (2009). "The risk of melamine-induced nephrolithiasis in young children starts at a lower intake level than recommended by the WHO". Pediatric Nephrology. 25 (1): 135–41. doi:10.1007/s00467-009-1298-3. PMID 19727838. S2CID 360958.
  73. ^ Liu, J.-m.; Ren, A.; Yang, L.; Gao, J.; Pei, L.; Ye, R.; Qu, Q.; Zheng, X. (2010). "Urinary tract abnormalities in Chinese rural children who consumed melamine-contaminated dairy products: A population-based screening and follow-up study". Canadian Medical Association Journal. 182 (5): 439–43. doi:10.1503/cmaj.091063. PMC 2842835. PMID 20176755.
  74. ^ "About melamine". Irmm.jrc.ec.europa.eu. February 2, 2012. Archived from the original on February 12, 2012. Retrieved June 20, 2012.
  75. ^ Breidbach, A., Bouten, K., Kroger, K., Ulberth, F. "Melamine Proficiency Test 2009". ec.europa.eu Archived October 15, 2009, at the Wayback Machine
  76. ^ U.S. FDA Laboratory Information Bulletin No 4421 – "US FDA/CFSAN - Determination of Melamine and Cyanuric Acid Residues in Infant Formula using LC-MS/MS - Lib. 4421". Archived from the original on October 10, 2008. Retrieved October 16, 2008.
  77. ^ Japanese Ministry of Health, Labor and Welfare. forth.go.jp
  78. ^ Zwitterionic HILIC separation of melamine and cyanuric acid – "Strategies for Determination of Melamine by HILIC". October 3, 2008. Archived from the original on October 6, 2008. Retrieved October 16, 2008.
  79. ^ Hodge, James (December 12, 2008). "Dairy detection: monitoring melamine in milk". Chemical Science. No. 2. Royal Chemical Society, RCS Publishing. Retrieved January 4, 2009.
  80. ^ Zhu, Liang; Gamez, Gerardo; Chen, Huanwen; Chingin, Konstantin; Zenobi, Renato (2009). "Rapid detection of melamine in untreated milk and wheat gluten by ultrasound-assisted extractive electrospray ionization mass spectrometry (EESI-MS)". Chemical Communications (5): 559–61. doi:10.1039/b818541g. PMID 19283290.
  81. ^ Abedini, R.; Jahed Khaniki, G.; Molaee Aghaee, E.; Sadighara, P.; Nazmara, S.; Akbari-Adergani, B.; Naderi, M. (June 2021). "Determination of melamine contamination in chocolates containing powdered milk by high-performance liquid chromatography (HPLC)". Journal of Environmental Health Science & Engineering. 19 (1): 165–171. doi:10.1007/s40201-020-00590-w. PMC 8172743. PMID 34150227.
  82. ^ Huang, Guangming; Ouyang, Zheng; Cooks, R. Graham (2009). "High-throughput trace melamine analysis in complex mixtures". Chemical Communications (5): 556–8. doi:10.1039/b818059h. PMID 19283289.
  83. ^ Melaminometer
  84. ^ McKenna, Phil (January 7, 2009). "Rise of the garage genome hackers". New Scientist. Retrieved February 17, 2009.
  85. ^ Marcus, Wohlsen (December 26, 2008). "Amateurs are trying genetic engineering at home". Copyright 2008 The Associated Press. Retrieved February 17, 2009.
  86. ^ Ishiwata H, Inoue T, Yamazaki T, Yoshihira K (1987). "Liquid chromatographic determination of melamine in beverages". Journal of the Association of Official Analytical Chemists. 70 (3): 457–460. doi:10.1093/jaoac/70.3.457. PMID 3610957.
  87. ^ Sancho, J.V.; Ibáñez, M.; Grimalt, S.; Pozo, Ó.J.; Hernández, F. (2005). "Residue determination of cyromazine and its metabolite melamine in chard samples by ion-pair liquid chromatography coupled to electrospray tandem mass spectrometry". Analytica Chimica Acta. 530 (2): 237–243. doi:10.1016/j.aca.2004.09.038. INIST 16514561.
  88. ^ "Cyromazine and Melamine" (PDF). USDA FSIS. July 1991. Archived from the original (PDF) on June 16, 2007. Retrieved April 27, 2007.
  89. ^ "Chemistry Laboratory Guidebook". USDA FSIS. Retrieved April 27, 2007.
  90. ^ "HPLC Determination of Melamine, Ammeline, Ammelide, and Cyanuric Acid Contamination in Wheat Gluten and Rice Protein Concentrate". U.S. Food and Drug Administration. April 25, 2007. Archived from the original on December 20, 2008. Retrieved May 9, 2007.
  91. ^ He, Lili; Liu, Yang; Lin, Mengshi; Awika, Joseph; Ledoux, David R.; Li, Hao; Mustapha, Azlin (2008). "A new approach to measure melamine, cyanuric acid, and melamine cyanurate using surface enhanced Raman spectroscopy coupled with gold nanosubstrates". Sensing and Instrumentation for Food Quality and Safety. 2: 66–71. doi:10.1007/s11694-008-9038-0. S2CID 93425738.
  92. ^ Lin, M.; He, L.; Awika, J.; Yang, L.; Ledoux, D.R.; Li, H.; Mustapha, A. (2008). "Detection of Melamine in Gluten, Chicken Feed, and Processed Foods Using Surface Enhanced Raman Spectroscopy and HPLC". Journal of Food Science. 73 (8): T129-34. doi:10.1111/j.1750-3841.2008.00901.x. PMID 19019134.
  93. ^ European Commission decision (2008/798/EC) imposing special conditions governing the import of products containing milk or milk products originating from China
  94. ^ Baselt RC (2014). Disposition of toxic drugs and chemicals in man. Seal Beach, Ca.: Biomedical Publications. pp. 1213–1214. ISBN 978-0-9626523-9-4.
  95. ^ Silly, Fabien; Shaw, Adam Q.; Castell, Martin R.; Briggs, G. A. D.; Mura, Manuela; Martsinovich, Natalia; Kantorovich, Lev (2008). "Melamine Structures on the Au(111) Surface". J. Phys. Chem. C. 112 (30): 11476–11480. doi:10.1021/jp8033769.
  96. ^ Schmitz, Christoph H.; Ikonomov, Julian; Sokolowski, Moritz (2011). "Two commensurate hydrogen-bonded monolayer structures of melamine on Ag(111)". Surface Science. 605 (1–2): 1–6. Bibcode:2011SurSc.605....1S. doi:10.1016/j.susc.2010.09.006.
  97. ^ Šimėnas, M.; Tornau, E. E. (2014). "A model of melamine molecules ordering on metal surfaces". J. Chem. Phys. 141 (5): 054701. Bibcode:2014JChPh.141e4701A. doi:10.1063/1.4891245. PMID 25106594.
  98. ^ Mura, M.; Martsinovich, N.; Kantorovich, L. (2008). "Theoretical study of melamine superstructures and their interaction with the Au(111) surface". Nanotechnology. 19 (46): 465704. Bibcode:2008Nanot..19T5704M. doi:10.1088/0957-4484/19/46/465704. PMID 21836259. S2CID 25890258.
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