Simultaneous Determination of Melamine, Ammelide, Ammeline, and Cyanuric Acid in Milk and Milk Products by Gas Chromatography-tandem Mass Spectrometry

Objective To develop an analytical method for simultaneously qualitative and quantitative determination of melamine and triazine-related by-products including ammelide, ammeline, and cyanuric acid in milk and milk products by gas chromatography- tandem mass spectrometry （GC-MS/MS）. Methods Melamine and triazine-related by-products namely ammelide, ammeline and cyanuric acid in the samples were extracted in a solvent mixture of diethylamine, water, and acetonitrile （10：40：50, V/V/V）. After centrifugation, an aliquot of the supernatant was evaporated to dryness under a gentle stream of nitrogen gas, and then melamine and triazine-related by-products were derivatized using BSTFA with 1% TMCS. The derivatives of melamine and its analogues were determined by gas chromatography/tandem mass spectrometry using multiple reactional monitoring （MRM） with 2, 6-Diamino-4-chloropyrimidine （DACP） being used as an internal standard. Results The linear detectable ranges were from 0.004 mg/kg to 1.6 mg/kg for melamine, ammelide, ammeline, and cyanuric acid with a correlation coefficient no less than 0.999. The recovery rates of the tour compounds in spiked blank milk powder at concentrations 0.5, 1, 2 mg/kg were between 61.4%-117.2%, and the relative standard deviation was no more than 11.5% （n=6）. The detection limits of melamine, ammelide, ammeline and cyanuric acid in milk powder were 0.002 mg/kg with a ratio of signal to noise of 3. Conclusion This GC-MS/MS method for simultaneous determination of melamine, ammelide, ammeline, and cyanuric acid in milk and milk products is sensitive and specific.

Induction of Apoptosis in the Immature Mouse Testes by a Mixture of Melamine and Cyanuric Acid

The toxicity of melamine has attracted much attention since the recent outbreaks of renal injury in pets and infants. Previous studies indicated that melamine by itself had low toxicity, whereas a mixture of melamine and cyanuric acid （M＋CA） could cause serious renal damage. At present, most researches on the toxicity of M＋CA are focused on the kidney. However, little is known about the adverse effects of this mixture on the reproductive system. In the present study, the toxicity of M＋CA to testes was investigated. Immature male mice were orally dosed with 0, 0.6, 3, and 15 mg kg-1 d-1 of a 1：1 M＋CA for 28 d. Pathological changes occurred in germ cells, such as loose arrangement, reduced numbers and karyopyknosis, indicating that this mixture was toxic to spermatogenesis. Compared with the control group, the TUNEL- positive germ cells increased significantly and the ratio of Bcl-2 to Bax, total antioxidant capacity and superoxide dismutase activity decreased significantly in the 3 and 15 mg kg-1 d- M＋CA treated group, while the activities of caspase-3, caspase- 8 and caspase-9 remained unchanged. The results suggest that M＋CA can induce apoptosis in the mice testes. The downregulation of Bcl-2/Bax and oxidative stress may play a pivotal role in the induction of apoptosis by M＋CA in mice testes.

Synthesis and Crystal Structure of a Complex of Melamine with Benzoic Acid

A new complex of melamine（MA） with benzoic acid（HBA） was prepared, affording [（HMA＋）（BA-）]-2H2O. Each HBA molecule is deprotonated and one triazine nitrogen atom of MA is protonated. The adjacent HMA＋ cations are related via an inverse center to form ribbons with a pair of N--H…N hydrogen bonds. COO- groups of BA- anions are hydrogen bonded to alternate sides of the （HMA＋）∞ ribbons to generate indention ID tapes, which are extended into a 3D structure via N--H…O- and N--H…OW hydrogen bonds and π-π stacking interactions. Predominant patterns of the hydrogen bond present in the complex are anion/water and amino/water tape structures. The hydrogen-bonding patterns consist of alternate 6, 10-membered rings sharing two edges. Infrared（IR） spectroscopy conforms that proton transfer has taken place in the complex.

Hydrogen-bonded Supramolecular Rosette Ribbon Constructed from Melamine with Isophthalic Acid

The new complex of melamine （MA） with isophthalic acid （H2IA）, [（HMA^＋）- （HIA^-）]·2H2O, has been prepared and its structure was characterized by X-ray crystallography. The crystal is of triclinic, space group P^-1 with a = 7.0228（6）, b = 9.1706（8）, c = 12.170（1） A, α = 95.337（2）, β = 105.247（2）, γ = 97.813（2）^o, V = 742.3（1） A ^3, Mr= 328.30, Z = 2, Dc = 1.469 g/cm^3, ;λ = 0.71073 A,μ（MoKa） = 0.121 mm^-1 and F（000） = 344. The structure was refined to R = 0.0389 and wR = 0.1093 for 2513 observed reflections with I 〉 2σ（I）. Melamine dimer and isophthalic acid anion are interlinked by N-H…N and N-H…O hydrogen bonds, resulting in a 1D rosette ribbon in which water molecules and amino groups are self-assembled into quasihexagonal patterns.

Hydrogen-bonding Networks in Cocrystal of Melamine and 4-Fluoro-benzoic Acid

A novel interpenetrating structure [（HMA^＋）（FB^- ）] ·2H2O of melamine（MA） with 4-fluoro-benzoic acid （HFB） was synthesized. It crystallized in the monoclinic system with space group P21/c. The complex has a interpenetrating 2D structure with hydrogen-bonded grid networks. Carboxylic acid to melamine proton transfer occurs in the complex. The adjacent HMA^＋ cations related by an inverse center form cationic [HMA^＋]∞ ribbons via a pair of N-H…N hydrogen bonds. Adjacent FB-anions are paired by C-H…F hydrogen bonds to form dimers, which are connected to [HMA^＋]∞ ribbons through N-H…O interactions. The supramolecular features in the complex are guided by control of strong N-H…N, N-H…O and O-H…O hydrogen bonds, as well as highly directional weak C-H…F interactions and aromatic π-π stacking interactions.

Research Progress on Detection Methods of Melamine and Cyanuric Acid Residue in Dairy Products and Feedstuff

[Objective] More accurate, rapid and sensitive method of melamine and cyanuricacid residue in dairy products and feedstuff were re- viewed. [ Method] Physicochemical properties, metabolism, uses, harm and detection methods of melamine and cyanuric acid were analyzed and described. [ Result] Melamine and cyanuric acid, when used alone, were slightly toxic, but long -term intake could lead to animal reproductive and urinary system damage. [ Condusion] Establishing a more sensitive, fast and easy to popularize detection method for elarnine and cyanuricacid res- idue in dairy products and feedstuff was necessary.

Biodegradation of Melamine and Cyanuric Acid by a Newly-Isolated <i>Microbacterium</i>Strain

We searched for a superior melamine-degrading bacterium for the bioremediation of melamine. Cyanuric acid, which is a by-product produced during the biodegradation of melamine, shows strong nephrotoxicity. Therefore, the melamine-degrading bacterium is also required to show a high ability to degrade cyanuric acid. We selected a melamine-degrading strain (MEL1) among ten cyanuric acid-degrading bacteria isolated from the soil. The species of MEL1 strain was Microbacterium esteramaticum or was extremely similar to that species, and the enzymatic activity of the melamine deaminase in the MEL1 strain was similar to that in the NRRLB-12227 strain. The ability of the MEL1 strain to degrade cyanuric acid was higher than its ability to degrade melamine, and therefore, the accumulation of by-products (ammeline, ammelide and cyanuric acid) during the degradation of melamine was minimal. These results suggest that the MEL1 strain is useful for the bioremediation of melamine.

An Evaluation of Genotoxicity and Cytotoxicity of Melamine in Combination with Cyanuric Acid at Three Mass Ratios

Melamine in combination with cyanuric acid has been considered to be more toxic than either melamine or cyanuric acid alone. The objective of this study was designed to evaluate the combined genotoxicity and cytotoxicity of melamine （M） and cyanuric acid （C） at three mass ratios （1：1, 1：2, 2：1）. MC （1：1）, MC （1：2）, and MC （2：1） were evaluated for their potential genotoxic risk, at gene level by Ames test, and at chromosomal level by micronucleus test. In order to evaluate cytotoxicity in HEK-293 cells, the MTT assay was included. Western blot was also employed to investigate the renal injury molecule-1 （Kim-1） expression in HEK-293 cells exposed to MC. Neither genotoxicity at gene level nor at chromosomal level was observed for MC （1：1）, MC （1：2）, and MC （2：1）. Based on MTT assay, three ratios of MC at 82.5 and 165 μg/mL slightly inhibited viability of HEK-293 cells （P〈0.05）. MC （1：1） at 41.25 and 82.50 IJg/mL could elevate the Kim-1 expression in HEK-293 cells.

Voltammetric Study of the Interaction between Melamine and DNA on a Carboxylic Acid-Functionalized Nano-Fe₃O₄Modified Electrode and Its Analytical Application for Melamine Determination in Liquid Milk Samples

Carboxylic acid-functionalized nano-sized magnetic composite polymers (COOH-NMPs) were synthesized and used for the preparation of the modified glassy carbon electrode, i.e., COOH-NMPs/GCE and DNA/COOH-NMPs/GCE. The electrochemical behaviors of melamine (MM) were investigated on COOH-NMPs/GCE by cyclic voltammetry (CV) in both cases of DNA in the solution and immobilized on the electrode surface. The electron transfer coefficient (a) and the rate constant (ks) kept unchanged in the absence and presence of DNA. Based on the electrochemical properties of the interaction of MM on the surface of the DNA/COOH-NMPs/GCE, a direct method for the determination of MM in liquid milk was established. The detection limit of this method was 2.0 ng·L﹣1, with average recoveries at 95.9% - 104.2% and RSD at 4.5% - 8.2%. The proposed method was provided to have a good accuracy, high stability and good reproducibility with a simple and environmental friendly process. 10 kinds of liquid milk samples bought from the market randomly were tested, and only 1 of them was found at relatively low level of MM residue with the amount of 0.12 ug·L﹣1.

A Survey on Occurrence of Melamine and Its Analogues in Tainted Infant Formula in China

Objective To investigate the occurrence and concentrations of melamine and its analogues in tainted infant formula and to identify the etiologic factors for the urinary stones epidemic in infants and young children in China in 2008. Methods Sanlu infant formula samples were collected from families of the affected children in Gansu province, and markets in Gansu and Hebei provinces and Beijing city. Melamine and its analogues, including cyanuric acid, ammeline, and ammelide were measured by gas chromatography/tandem mass spectrometry. Results High prevalence and concentrations of melamine were found in Sanlu infant formula samples, with low concentrations of cyanuric acid, ammeline and ammelide. Melamine were detected in 87 out of 111 Sanlu infant formula samples with a range of 118 to 4 700 mg/kg, Conclusion The results provide strong evidence for melamine as the etiological factor for the urinary stones epidemic in infants and young children in China in 2008.

Synthesis and characterization of PMoV/Fe_3O_4/g-C_3N_4 from melamine:An industrial green nanocatalyst for deep oxidative desulfurization

A facile approach to the preparation of a novel magnetically separable H_5PMo_（10）V_2O_（40）/Fe_3O_4/g-C_3N_4（PMoV/Fe_3O_4/g-C_3N_4） nanocomposite by chemical impregnation is demonstrated.The prepared nanocomposite was characterized and its acidity was measured by potentiometric titration.PMoV/Fe_3O_4/g-C_3N_4 showed high catalytic activity in the selective oxidative desulfurization of sulfides to their corresponding sulfoxides or sulfones.The catalytic oxidation of a dibenzothiophene（DBT）-containing model oil and that of real oil were also studied under optimized conditions.In addition,the effects of various nitrogen compounds,as well as the use of one- and two-ring aromatic hydrocarbons as co-solvents,on the catalytic removal of sulfur from DBT were investigated.The catalyst was easily separated and could be recovered from the reaction mixture by using an external magnetic field.Additionally,the remaining reactants could be separated from the products by simple decantation if an appropriate solvent was chosen for the extraction.The advantages of this nanocatalyst are its high catalytic activity and reusability;it can be used at least four times without considerable loss of activity.

Facile oxalic acid-assisted construction of laminated porous N-deficient graphitic carbon nitride: Highly efficient visible-light-driven hydrogen evolution photocatalyst

The laminated porous N-deficient g-C3N4(CN–H)is successfully synthesized by a facile two-step hydrothermal calcination method using oxalic acid-assisted melamine as the precursor.Compared with pristine g-C3N4(224μmol g-1h-1),the CN–H shows superior photocatalytic hydrogen production activity(up to 728μmol g-1h-1),which is three times higher than the unmodified counterpart.To draw out the multifaceted influences of oxalic acid modification on the visible-light-induced photocatalytic activity,various techniques are utilized to investigate the formation mechanism,structural characteristics and photoelectrical properties of CN–H.The results indicate that the addition of a trace amount of oxalic acid to the precursor melamine results in a g-C3N4 structure possessing the advantage of both nitrogen defects and laminated porosity.These properties can enlarge specific surface areas of g-C3N4,enhance an efficient separating of photogenerated electron-hole pairs and extend the range of spectral response,all contributing to the enhancement of the visible-light-induced photocatalytic activity.

Melamine trisulfonic acid:A new,efficient and recyclable catalyst for the synthesis of 3,4-dihydropyrimidin-2(1H)-ones/thiones in the absence of solvent

Melamine trisulfonic acid（MTSA） can be used as an efficient and recyclable catalyst for the promotion of the synthesis of 3,4- dihydropyrimidin-2（1H）-ones/thiones（DHPMs） in the absence of solvent.All reactions were performed at 80℃in good to high yields.

化工固体废弃物的资源化利用研究

在现代生产过程中,化工固体废弃物引起了严重的环境污染问题,为了建设环保社会,同时减少资源浪费,对化工固体废弃物的回收与利用成了备受关注的课题,本文介绍了化工固体废弃物的研究现状与资源利用情况,以三聚氰胺生产过程中产生的废渣为例,介绍了废渣成分以及三聚氰酸的发展趋势,并通过研究制备工艺确定了废渣合成三聚氰酸的最佳条件,为固体废弃物的资源化利用提供了实践证明。

化工固体废弃物的资源化利用

为了解决化工固体废物处理不当对环境造成污染以及资源浪费的问题,以三聚氰胺废渣为例对固体废弃物开展资源化利用研究:结合三聚氰胺废渣的特点制定了预处理方案和流程;对三聚氰胺制备三聚氰酸的实验方案进行设计;通过控制变量原则分别对反应温度、反应时间以及硫酸氢钠添加量对三聚氰酸产率的影响开展实验研究。研究成果可指导三聚氰胺化工固体废弃物的资源化利用。

Microwave promoted rapid dehydration of aldoximes to nitriles using melamine-formaldehyde resin supported sulphuric acid in dry media

A simple and convenient procedure for the synthesis of nitriles by dehydration of aldoxime using supported sulphuric acid on melamine-formaldehyde resin （MFR） under solvent-free condition has been developed. A variety of aromatic and aliphatic aldoximes were converted to the corresponding nitriles. The resin was recovered and reused for subsequent reactions. ~ 2011 Ramin Rezaei. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.

一种氮-硫协同高效三聚氰胺苯磺酸盐阻燃剂制备及应用研究

本研究合成了一种氮-硫协同高效三聚氰胺苯磺酸盐(MBSA),并运用傅里叶变换红外光谱和热重分析仪对其进行了结构和性能表征。将MBSA添加到聚酰胺6(PA6)中,通过UL-94评级和熔融指数评估了MBSA/PA6复合材料的阻燃性能和加工性能。结果显示,MBSA表现出优异的热稳定性,其分解温度显著高于PA6的加工温度,适合于高温条件下的加工应用。当MBSA添加量为8%时,MBSA/PA6复合材料达到了UL-94 V0等级。此外,MBSA的加入显著提高了复合材料的熔融指数,改善了其加工性能,有利于工业生产和成型。本研究揭示了MBSA作为PA6阻燃添加剂的巨大潜力,为提升聚酰胺类复合材料的性能和应用提供了新的途径和策略。

典型的三聚氰胺致幼儿肾结石红外光谱分析

从云南省第一人民医院得到经过医学证实的典型三聚氰胺肾结石，将2 mg肾结石与200 mg KBr一同放入玛瑙研钵中研碎，进行压片。用Perkin-Elemer公司生产的spectrum 100光谱仪得到了该结石的红外光谱。吸收峰在4 000～2 000 cm-1之间有3 487，3 325, 3 162, 2 788 cm-1，在1 700～1 000 cm-1之间有1 694，1 555，1 383，1 340，1 189，1 122 cm-1，在1 000～400 cm-1之间有993，782，748，709，624，585，565，476 cm-1。结石的红外光谱经过与文献报道的饲喂含氰尿酸、三聚氰胺宠物饲料后猫的肾结石的红外光谱图及普通人肾结石的红外光谱图对比，相差很大，说明该患儿结石与宠物结石及普通人肾结石的成分相同的可能性不大;分别与三聚氰胺与尿酸的红外光谱图对比，各有50%的相似性; 将三聚氰胺、尿酸按1∶1混合后，红外光谱出现的峰在4 000～2 000 cm-1 之间有3 469，3 419，3 333，3 132，3 026，2 827 cm-1， 在1 700～1 000 cm-1之间有1 696, 1 656, 1 555, 1 489, 1 439, 1 350, 1 311, 1 198, 1 124, 1 028 cm-1, 在1 000～400 cm-1之间有993，878，814，784，745，708，619，577，475 cm-1，将其与结石的红外光谱对比，发现两张图谱有83.3%的相似性，由此得出典型三聚氰胺尿结石的主要成分为三聚氰胺和尿酸。

g-C_3N_4/TiO_2复合纳米材料的制备及其光催化性能分析

以工业偏钛酸为钛前驱体,三聚氰胺为氮源,制备了g-C3N4/TiO2复合光催化剂;用X射线衍射(XRD)能谱、X射线光电子(XPS)能谱、傅里叶红外变换光谱(FT-IR)及热重和差示扫描量热分析(TGDSC)、透射电子显微镜(TEM)、紫外-可见吸收(UVVis)光谱、三维荧光(FS)光谱、物理吸附仪(BET)等对催化剂进行了表征。可见光催化实验表明,三聚氰胺与工业偏钛酸质量比为1,500℃煅烧制得的g-C3N4/TiO2复合催化剂对亚甲基蓝表现出最佳的光催化活性,300min内对10mg/L亚甲基蓝溶液的降解率达到83%。

阻燃剂三聚氰胺聚磷酸盐的合成

以三聚氰胺和多聚磷酸为原料,合成了三聚氰胺聚磷酸盐阻燃剂,收率为90.4%。并通过红外光谱(IR)及热分解(DSC)对其结构、性能进行了表征。分别讨论了原料摩尔比、反应时间、溶剂等对产物的影响,确定最佳反应条件为:n(三聚氰胺)∶n(多聚磷酸)=3∶1,反应时间16 h,溶剂为冰醋酸。