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.

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.

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.

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.

Enhanced Crystallization Rate of Biodegradable Poly(ε-caprolactone) by Cyanuric Acid as an Efficient Nucleating Agent

The influence of cyanuric acid（CA） as an efficient nucleating agent on the crystallization behavior and morphology of biodegradable poly（ε-caprolactone）（PCL） was extensively studied in this work with several techniques for the first time. The nonisothermal melt crystallization behavior and overall isothermal melt crystallization rate of PCL were significantly enhanced by only a small amount of CA. The addition of CA apparently improved the nonisothermal melt crystallization peak temperature, overall isothermal melt crystallization rate, and nucleation density of PCL spherulites, but did not modify the crystallization mechanism and crystal structure of PCL, indicating that CA was an efficient nucleating agent for the crystallization of PCL. The possible nucleation mechanism of CA on the crystallization of PCL was also discussed on the basis of their crystal structures.

Determination of Cyanuric Acid in Milk Powder and Swimming Pool Water by Ion-pair Reversed-phase Liquid Chromatography

An ion-pair reversed-phase high-performance liquid chromatographic method, using tetrabutylammonium bromide （TBAB） as ion-pair reagent, has been developed for the analysis of cyanuric acid （CA） in milk powder and swimming pool water. It was found that the effect of the concentrations of ion-pair reagent on the retention of cyanuric acid was different for standard solution and different real samples. The separation was carried out on a reversed-phase C18 column with 85 ： 15 （V/V） water-acetonitrile （ACN） containing different concentration of TBAB as mobile phase for different samples. The linear range of the calibration curve for CA was 0.1-100 mg·L^-1 The detection limits calculated at S/N=3 was 0.11 mg-L^-1 for the analysis of milk powder and 0.31 mg·L^-1 for the analysis of swimming pool water, respectively. The method was successfully applied to the analysis of CA in milk powder and swimming pool water.

A Two-coordinate Copper（Ⅰ） Complex Constructed from Cyanuric Acid and 4,4＇-Bipyridyl： Synthesis, Structure and Photoluminescence

A two-coordinate copper（Ⅰ） complex, Cu2（bipy）（H2L）2 （1） （H3L=cyanuric acid, bipy=4,4＇-bipyridyl）, which exhibits strong photoluminescence, has been synthesized under hydrothermal conditions and structurally characterized by single crystal X-ray diffraction. The compound crystallizes in the monoclinic space group P21/n, with cell parameters： Mr= 539.42, a= 13.4806（5）A↑°, b=4.5234（2） A↑°, c= 15.4952（8）A↑°,β = 105.526（3）°, V=910.39（7）A↑°^3, Z=2 and μ=3.52 mm^ -1. In the structure the two Cu（Ⅰ） ions are bridged by bipy to form a two-coordinate copper（Ⅰ） dimer. The adjacent dimer units are connected by hydrogen bonding interactions, resulting in 1D zigzag chains along the c axis. 1 emits intense yellow light when excited with UV light.

The contribution of mediated oxidation mechanisms in the electrolytic degradation of cyanuric acid using diamond anodes

In this work, the contribution of mediated oxidation mechanisms in the electrolytic degradation of cyanuric acid using boron-doped diamond（BDD） anodes was investigated in different electrolytes. A complete mineralization of cyanuric acid was obtained in Na Cl;however lower degrees of mineralization of 70% and 40% were obtained in Na2SO4 and Na Cl O4, respectively. This can be explained by the nature of the oxidants electrogenerated in each electrolyte. It is clear that the contribution of active chlorine（Cl2, HCl O, Cl O-）electrogenerated from oxidation of chlorides on BDD is much more important in the electrolytic degradation of cyanuric acid than the persulfate and hydroxyl radicals produced by electro-oxidation of sulfate and water on BDD anodes. This could be explained by the high affinity of active chlorine towards nitrogen compounds. No organic intermediates were detected during the electrolytic degradation of cyanuric acid in any the electrolytes, which can be explained by their immediate depletion by hydroxyl radicals produced on the BDD surface. Nitrates and ammonium were the final products of electrolytic degradation of cyanuric acid on BDD anodes in all electrolytes. In addition, small amounts of chloramines were formed in the chloride medium. Low current density（≤ 10 m A/cm2） and neutral medium（p H in the range 6–9） should be used for high efficiency electrolytic degradation and negligible formation of hazardous chlorate and perchlorate.

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.

Atrazine biodegradation efficiency, metabolite detection, and trzD gene expression by enrichment bacterial cultures from agricultural soil

Atrazine is a selective herbicide used in agricultural fields to control the emergence of broadleaf and grassy weeds. The persistence of this herbicide is influenced by the metabolic action of habituated native microorganisms. This study provides information on the occurrence of atrazine mineralizing bacterial strains with faster metabolizing ability. The enrichment cultures were tested for the biodegradation of atrazine by high-performance liquid chromatography(HPLC) and mass spectrometry. Nine cultures JS01.Deg01 to JS09.Deg01 were identified as the degrader of atrazine in the enrichment culture. The three isolates JS04.Deg01, JS07.Deg01, and JS08.Deg01 were identified as efficient atrazine metabolizers. Isolates JS04.Deg01 and JS07.Deg01 produced hydroxyatrazine(HA) N-isopropylammelide and cyanuric acid by dealkylation reaction. The isolate JS08.Deg01 generated deethylatrazine(DEA), deisopropylatrazine(DIA), and cyanuric acid by N-dealkylation in the upper degradation pathway and later it incorporated cyanuric acid in their biomass by the lower degradation pathway. The optimum pH for degrading atrazine by JS08.Deg01 was 7.0 and 16S rDNA phylogenetic typing identified it as Enterobacter cloacae strain JS08.Deg01. The highest atrazine mineralization was observed in case of isolate JS08.Deg01, where an ample amount of trzD mRNA was quantified at 72 h of incubation with atrazine. Atrazine bioremediating isolate E. cloacae strain JS08.Deg01 could be the better environmental remediator of agricultural soils and the crop fields contaminated with atrazine could be the source of the efficient biodegrading microbial strains for the environmental cleanup process.

A review of traditional and novel detection techniques for melamine and its analogues in foods and animal feed

Melamine,a nitrogen-rich chemical,has received much attention in recent years due to a series of highly publicized food safety incidents,including 2007 pet food recalls in North America and 2008 melamine contamination in milk,infant formula,and other milkderived products in China.Current analytical methods for testing melamine are time-consuming,expensive,and labor-intensive.Therefore,there is an increasing interest in the food science and analytical chemistry field to develop simple,quick,sensitive,and cost-effective methods for detection of melamine and its analogues(e.g.,cyanuric acid,melamine cyanurate,ammelide,and ammeline)in food ingredients,processed food,and animal feed.This review aims to summarize traditional and novel analytical techniques that have been used or show great potential to detect,characterize,and quantify melamine and its analogues in foods and animal feed.