宠物食品中三聚氰胺及三聚氰酸的液相色谱串联质谱法分析

A rapid and sensitive LC-MS/MS method was established to analyze melamine and cyanuric acid in pet food and its ingredients.HILIC mechanism was utilized to separate small highly polar compounds such as melamine and cyanuric acid.In comparison with US FDA recognized GCMS and LC methods,it turned out that the current technique is superior with easy sample preparation,and the sensitivity and selectivity was found satisfactory.The LOD was 50 ng·L-1 for melamine and 1 μg·L-1 for cyanuric acid,respectively.

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.

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.

Flame retardant polyamide 6 by in situ polymerization of ε-caprolactam in the presence of melamine derivatives

An improved method for preparing melamine cyanurate （MCA） based flame retardant polyamide 6 （FRPA6） materials has been proposed. This processing method, i.e., improved in situ polymerization, was used to synthesize flame retardant PA6. In situ formed MCA nanoparticles were supposed to be linked to PA6 chains in the ε-caprolactam hydrolytic polymerization system to obtain startype polymers for the first time. Through TEM photographs, it can be found that the in situ formed MCA nanoparticles with diametric size of less than 50 nm, are nanoscaled, highly uniformly dispersed in the PA6 matrix. Synthesized flame retardant PA6 have good fire performance which can achieve UL-94 V-0 rating at 1.6 mm thickness with the presence of 7.34 wt.% MCA in the matrix.

Wet cyanuric chloride promoted efficient synthesis of amidoalkyl naphthols under solvent-free conditions

An efficient and direct procedure has been developed for the preparation of amidoalkyl naphthols by a one-pot condensation of aryl aldehydes, 2-naphthol and urea or amides, in the presence of wet-cyanuric chloride （wet-TCT） as a catalyst. The reactions were carried out under solvent-free media. The present methodology offers several advantages such as excellent yields, simple procedure and eco-friendly reaction condition.

Crystal and Molecular Structure of Cyanuric Acid

The title compound [C3H3N3O3·2H2O] was synthesized by the reaction of urea with hydrogen peroxide, and characterized by elemental analysis, infrared spectra and nuclear magnetic resonance. The crystal belongs to monoclinic system,space group C2/c, with a=12. 538(3)i, b=6. 685(1),c=8.807 (3) , β= 116.11(2)°;V=662. 9(4), Z=4, Mr=165.11, Dc=1.65g/cm3, (MOKα)=0. 71069,μ=1. 47 cm-1, F(000) = 344,final R=0. 046 and Rω=0.061 for 493 observable reflections with I>3σ(I). All atoms lie in plane giving the molecule a planar configuration. The bond length of C-O is 1.214(3), C-N is 1.366(3). Every two cyan-uric molecules in the cell are connected by two intermolecular hydrogen bonds N-H…O, with N…O distance of 2.763 , N-H…O angle of 180.0°.

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.

Investigations on the Degradation of Triazine Herbicides in Water by Photo-Fenton Process

In this work, the degradation of 2-chloro-4,6-diamino-1,3,5-triazine in aqueous solutions by photo-Fenton process has been investigated. The preliminary results have shown that the degradation of 2-chloro-4,6-diamino-1,3,5-triazine by photo-Fenton process is more rapid and more effective than Fenton and UV/H2O2 processes. The effects of certain experimental parameters on kinetics and efficiency of the degradation of 2-chloro-4,6,-diamino-1,3,5-triazine by photo-Fenton process, have been evaluated. Under optimal conditions, photo-Fenton process achieved more than 90% of chloride release and about 30% of nitrate formation. The results of total organic carbon (TOC) and total Kjeldahl nitrogen (TKN) analyses have shown that no carbon dioxide and ammonia are formed during photo-Fenton treatment of aqueous solutions containing 40 mg/L triazine. These results indicate that only substituent groups of triazine ring are released;however, nitrogen atoms of triazine ring remain unaffected. A simple mechanism of degradation of 2-chloro-4,6-diamino-1,3,5-triazine has been proposed. The degradation starts by a rapid release of chlorine atoms as chloride ions to form 2-hydroxy-4,6-diamino-1,3,5-triazine. The amino groups of 2-hydroxy-4,6-diamino-1,3,5-triazine undergo are oxidized into nitro groups by hydroxyl radicals to form 2-hydroxy-4,6-dinitro-1,3,5-triazine which undergoes a slow release of nitro groups and their substitution with hydroxyl groups to form cyanuric acid and nitrate ions. The degradation of cyanuric acid by photo-Fenton process has also been investigated. The results of TOC and TKN analyzes show that no carbon dioxide is formed during the treatment.

A 100% Water Mobile Phase HPLC-PDA Analysis of Meamine and Related Analogues

This paper describes a reserved-phase high performance liquid chromatographic method for detecting melamine (MEL) and related analogues, cyanuric acid (CYA), ammeline (AML), and ammelide (AMD), using a 100% water mobile phase. Chromatographic separation was performed an Inertsil? ODS-4 (250 × 4.6 mm, 5 μm) with a water mobile phase and a photodiode-array detector. The monitoring wavelength was adjusted to 210 nm which represents an average maximum for all the analytes. The total run time was < 8 min. The method shows high stability, significant linearity and satisfactory sensitivity. The detection limits were established in the range 23 - 46 ng.mL–1. An inexpensive and harmless method for the simultaneous detection of MEL, CYA, AML, and AMD was developed and may be further applied to the quantification in foods.

PREPARATION AND ADSORPTION OF THIOUREA MODIFIED GLUTARALDEHYDE-CROSSLINKED CHITOSAN RESINS

The preparation and adsorption of thiourea modified glutaraldehyde-crosslinked chitosan resin （Thio-chitosan） using cyanuric chloride as activator was studied. The adsorptive capacity of thio-chitosan with 15% apparent degree of crosslinking （DC, mass ration of glutaraldehyde to chitosan） to Cu（Ⅱ） was 160mg/g （dry weight）. The adsorption of Cu（Ⅱ） was correlated with Freundlich and Langmuir isotherm equation. Cu（Ⅱ） adsorbed on thio-chitosan column （ 1cm×10cm） was eluted with 0.5mol/L H2SO4, 6mol/L HCI and 3% thiourea solution with the recovery of 88.3%, 86.1% and 95.3%, respectively. The thio-chitosan resin can be applied to the separation and recovery of metal ions.

Crystal Structure of Calcium Complex with Cyanuric Acid Ligand［Ca（C3H3N3O3－O）（H2O）6］［（OH）（C3H2N3O3）］

The title compound[Ca(C3H3N3O3)(H2O)6][(OH)(C3H3N3O3)] crystallizes in the triclinic system,space group P1,with a=6.501(5),b=10.814(6),c=11.803(1) A,α=103.64(1),β=92. 72(3),γ=98. 82(4)°,V=793- 9(7) A3,Dc=l.77 g/cm3,Z=2,Mr=422. 32,λ(MoKα)=0.71069 A,μ=4.65 cm-1,F(000)=440,final R=0.045 and Rω=0.058 for 3422 observable reflections with I≥3σ(I).In the complex cation [Ca (C3H3N3O3)(H2O)6]2+,the Ca2+ is coordinated by an oxygen atom from cyanuric acid ligand and six oxygen atoms from water molecules forming a distorted pentagonal bipyramid geometry.The complex anions, OH- and C3H2N3O3-,are bound with the complex cation[(Ca(C3H3N3O3)(H2O)6]2+ by electrostatic force to form the title compound.

Antimicrobial M aterials: Synthesis of Reactive 5,5-Dimethylhydantoin Derivative and Application in Cellulose with Dyeing Process

The efficient and regenerable antibacterial properties of Nhalamines make them an ideal candidate for parapretion of antimicrobial textiles. In this study,a 5,5-dimethylhydantoin-based reactive N-halamine precursor, 4-( 4-( 3-( 3-hydroxypropyl)-5,5-dimethylhydantoin)-6-chloro-1,3,5-triazinylamino)-benzenesulfonate( HTB), was synthesized and characterized by ~1H-NMR. The synthesized compound was coated to cotton fabrics via reactive dye dyeing process. The coated cotton showed excellent antimicrobial activities against S. aureus( Gram-positive) and E. coli O157: H7( Gram-negative) with short contact times after exposing to diluted household bleach. The treatment method used in this study has a small effect on the tensile strength of cotton fabrics. The durability and regenerability of the chlorinated cotton samples were tested.Although the chlorine content decreased towards washing and storage,almost all of the initial oxidative chlorine levels could be regained after rechlorination.

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.

Synthesis of a Fluorophore with Improved Optical Brightness

The synthesis and characterization of a novel fluorophore(1), with potential application as an optical brightener are reported. This compound was prepared by reacting 4,4-diaminostilbene-2,2-disulfonic acid with cyanuric chloride in the presence of Na2CO3 followed by the addition of trityl aniline. Solution and solid state fluorescence demonstrated a strong blue/purple emission centered at 450 nm. 1H-NMR spectroscopy, mass spectrometry analysis, elemental analysis, and DOSY-NMR were used for the characterization of the fluorophore.

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.

Formation of Hybrid Ring Structure of Cyanurate/Isocyanurate in the Reaction be-tween 2,4,6-Tris(4-Phenyl-Phenoxy)-1, 3,5-Triazine and Phenyl Glycidyl Ether

Reaction products of 2,4,6-tris(4-phenyl-phenoxy)-1,3,5-triazine derived from 4-phenylphenol cyanate ester and phenyl glycidyl ether were analyzed. In addition to an isocyanurate compound and an oxazolidone compound which were well known as reaction products of cyanate esters and epoxy resins, compounds with hybrid ring structure of cyanurate/isocyanurate were determined. Gibbs free energies of the compound having hybrid ring structure of cyanurate/isocyanurate with two isocyanurate moiety were found to be lower than that of the compound with cyanurate ring structure through calculations. Calculation data supported the existence of hybrid ring structure of cy-anurate/isocyanurate. It was revealed that isomerization from cyanurate to isocyanurate occurs via hybrid ring structure of cyanurate/isocyanurate in the reaction of aryl cyanurate and epoxy.

Synthesis and Surface Active Properties of Cyanuric Chloride-based Branched Surfactant

A series of novel branched sodium carboxylate surfactants were synthesized from cyanuric chloride, behera amine, alcohol amine and 1,4-Bis (3-aminopropyl) piperazine through seven steps, and the total yield is about 25%. The chemical structures of target products were confirmed by 1H NMR, 13C NMR, FT-IR and ESI-MS. Their critical micelle concentrations (CMC) were also determined by surface tension tests in the aqueous solutions at 22 ℃. The results showed that the CMC value of multi-carboxylate anionic surfactants decreased with the increase of hydroxyl. Additionally, the branched structure of end group can reduce surface tension more than straight-chain type, which was determined by γCMC. The decomposition temperature of the target compound was 250 ℃, which was also tested by TG/DTA curve.

Molar ratio induced crystal transformation from coordination complex to coordination polymers

Coordination complex of a copper cyanurate(Cu(Ⅱ)-CA) was transformed into coordination polymers upon the stimulus of extra Cu(Ⅱ) through “directed Ostwald ripening”. By increasing the molar ratio of Cu(Ⅱ) to CA, we obtained two coordination polymers with selective coordination sites: Cu(Ⅱ)-κ N(HCA)κ NCu(Ⅱ) and Cu(Ⅱ)-κ N(HCA)κ O-Cu(Ⅱ), which display disparate magnetic interactions.

Dilution Accelerates Crystallization:A Negative-Order Kinetic Coordination Reaction Induced by the Competitive Interplay of Dissociation and Complexation

Chemical reactions in homogenous systems are generally associated with positive-order kinetics;that is,the reaction rate increases with the increased concentration of reactants.In this work,we report a coordination reaction of Cu^(2+)ions,cyanuric acid(CA),and pyridine in aqueous solution which shows negative-order kinetics with respect to the concentration of pyridine.As the pyridine concentration increases,the complexation of CA with pyridine overwhelms its dissociation in water,resulting in the redistribution of CA;that is,CA is sealed in the pyridine phase by forming an unreactive hydrogenbonded complex.As a result,the number of accessible anionic CA for crystallization in water decreases,and thus the crystallization slows down and almost terminates.Further,the crystallization yields two types of crystals with similar structures but disparate colors(red and blue),and the origin is investigated by the ligand field analysis.