Development of a high performance liquid chromatography method and a liquid chromatography-tandem mass spectrometry method with pressurized liquid extraction for simultaneous quantification and confirmation of cyromazine, melamine and its metabolites in foods of animal origin

Simple and sensitive methods have been developed for simultaneous detection of cyromazine, melamine and their metabolites (ammeline, ammelide and cyanuric acid) in samples of animal origins. These include a high performance liquid chromatography (HPLC) method and a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method and are useful in regular monitoring and in toxicity studies of these molecules. Representative samples used in this study include muscles and livers of swine, bovine, sheep and chicken, kidneys of swine, bovine and sheep, and milk powder. A new sample preparation procedure with pressurized liquid extraction (PLE) at 1400psi and 70°C was investigated. Quantification of these five compounds by HPLC was achieved using an APS-2 column with UV detection at 230 nm. Limit of detection (LOD) was at 10 μgkg(-1), and limit of quantification (LOQ) was at 40 μgkg(-1). Recoveries of the five analytes in spiked samples ranged from 72.2% to 115.4% with RSD less than 12%. Confirmatory analysis of the analytes was performed using LC-MS/MS in selected reaction monitoring (SRM) mode. The LOD and LOQ were 5 μgkg(-1) and 15 μgkg(-1), respectively. This is the first simultaneous analysis of cyromazine, melamine, ammeline, ammelide and cyanuric acid residues in complex tissue samples using PLE and HPLC. It is expected that these methods will find many practical applications in evaluating the safety of cyromazine, melamine and their metabolites.     

Application of a modified enzyme-linked immunosorbent assay for 3-amino-2-oxazolidinone residue in aquatic animals

Furazolidone has been banned from use in food animals because of its carcinogenicity and mutagenicity, but its continued misuse is widespread in aquacultures. Therefore, there is an urgent need for a simple, reliable, and rapid method for the detection of its marker residue, 3-amino-2-oxazolidinone (AOZ), in aquatic products. In this regard, we modified a simplified indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) to address this need. A good linearity was achieved over a concentration range of 0.05-12.15 μg L⁻¹, and the IC₅₀ value was 0.96 μg L⁻¹. The sample preparation was simple and effective included water bath treatments, acid hydrolysis combined with overnight derivatization of AOZ by benzaldehyde. The limit of detection and the limit of quantification were 0.15 and 0.3 μg kg⁻¹. The recoveries of AOZ in all tissues were between 78.0-95.3% at the levels of 0.3, 1.0, and 2.0 μg kg⁻¹. The inter-assay variability was less than 19.1%. The modified ic-ELISA was applied in quantification of AOZ elimination in carp. The results showed that AOZ was quite difficult to eliminate. Good correlations of the results obtained by ELISA and LC-MS/MS were observed in incurred carp muscle (r = 0.9923) and carp plasma (r = 0.9915) at the levels of 2.5-571.8 μg kg⁻¹ (μg L⁻¹). Better results were obtained by modified ic-ELISA when compared with commercial ELISA kit. Therefore, the present assay is considered a rapid, accurate, reliable, and inexpensive method for the detection of furazolidone-residues in the edible tissues of aquatic animals.     

Synthesis and Properties of u-Oxamido Heterobinuclear Cu(Ⅱ)-Co(Ⅱ) Complexes

Three heterobinuclear complexes were synthesized, namely [Cu (oxpn) Co (L)2] (ClO4)2·xH2O(L= 2,2'-bipyridyl(bpy), 1,10-phenanthroline(phen) , and 5-nitro-1, 10-phenanthroline (NO2-phen)), where oxpn represents N, N'-bis(3-aminopropyl) oxam-ido. Based on 1R, elemental analysis, conductivity measurement and electronic spectra, these complexes were characterized by an extended oxamido-bridged structure with Cu(Ⅱ) in a planar environment and Co(Ⅱ) in a octahedral environment. The symmetry of the cation is very close to C2v.The complexes were also characterized with variable temperature (4~300K) magnetic susceptibility, and the data were fit for the susceptibility equation derived from spin Hamilton, H= -2JS1.S2-DSx12 by least square strategy. The exchange integral, J, was found to be -22.36 cm-1 (for bpy);-15.45 cm-1 (for phen); -19. 10cm-1(for NO2-phen), indicating that there is a weak antiferromagnetic spin-exchange interaction between the metal ions.     

Dinuclear iron (III) complex with a bridging diphenylphosphate and two terminal diphenylphosphate ligands

Ｐｕｒｐｌｅａｃｉｄｐｈｏｓｐｈａｔａｓｅ(ＰＡＰ)ｃａｔａｌｙｚｅｓｔｈｅｈｙｄｒｏｌｙｓｉｓｏｆａｃｔｉｖａｔｅｄｐｈｏｓｐｈｏｒｉｃａｃｉｄｅｓｔｅｒｓｉｎｃｌｕｌｄｉｎｇｎｕｃｌｅｏｓｉｄｅｄｉａｎｄｔｒｉｐｈｏｓｐｈａｔｅｓａｎｄａｒｙｌｐｈｏｓｐｈａｔｅｓｕｎｄｅｒａｃｉｄｉｃｃｏｎｄｉｔｉｏｎｓ[1].Ａｌｔｈｏｕｇｈｔｈｅｙｈａｖｅｂｅｅｎｉｓｏｌａｔｅｄｆｒｏｍａｖａｒｉｅｔｙｏｆｍａｍｍａｌｉａｎ,ｐｌａｎｔ,ａｎｄｍｉｃｒｏｂｉａｌｓｏｕｒｃｅｓ,ｏｎｌｙｔｈｅｅｎｚｙｍｅｓｉｓｏ…     

2，6─二甲酸─4─取代苯酚双缩苯甲酰肼双核铜（Ⅱ）配合物的合成与磁性

本文合成并表征了两个新的双核铜（Ⅱ）配合物：〔Ｃｕ２（Ｌ）（μ─Ｃｌ）Ｃｌ２〕，配体Ｌ为２，６─二甲酰─４─甲基苯酚双缩苯甲酰肼，取代基分别为氯（Ｌ１）和叔丁基（Ｌ２）．配合物具有相同的组成和配位构型．变温磁化率（４－３００Ｋ）测定结果表明，由于取代基不同，其磁交换参数分别为－４６．２ｃｍ（－１）（Ｌ１）和－５７．６ｃｍ（－１）（Ｌ２）．     

苯并咪唑双铜配合物合成表征和生物活性

本文报道三种新的Ｎ－羟乙基－Ｎ，Ｎ′，Ｎ′－三苯并咪唑甲基乙二胺双配合物合成和表征。变温磁化率分析结果表明配合和双铜离子间存在弱的反铁相互作用。ＥＳＲ结果示配合物中Ｃｕ－Ｎ键具部分共价性。对配合物儿茶酚酶活性，体外抗癌活性及农药活性测定结果表明配合物具一定催化活性和生物活性。     

Synthesis,characterization and lithium-intercalation properties of rod-like CaMoO<Subscript>4</Subscript> nanocrystals

Rod-like CaMoO₄ nanocrystals were synthesized via a template-based rheological phase reaction route as a novel method. The physical characterization was carried out by thermogravimetric/differential thermal analysis (TG/DTA), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and elected-area electron diffraction (SAED). A structure-directed role of hexamethylene tetramine (HMTA) was observed during the formation of CaMoO₄ nanocrystals. The electrochemical performance of CaMoO₄ as anode for lithium ion batteries has also been investigated by galvanostatic cycling and AC impedance spectroscopy. CaMoO₄/Li cell can deliver superior capacity than theoretical value in the initial cycle, and the much improved capacity was attributed to the contribution of oxygen besides the reduction of molybdenum during lithium insertion. Furthermore, a charge capacity of 276 and 438 mAh/g was retained after 50 cycles in the range of 0.01–2.50 V vs Li at a current density of 100 and 200 mA/g, respectively. The particle size and morphological properties were found to play an important role in fast lithium insertion/extraction performance and cycling stability at high rate.     

New types of heterospin complexes from trans-oxamido-bridged copper(II) binuclear units and nitronyl nitroxide radicals: crystal structure and magnetic characterization

Three new heterospin complexes derived from trans-oxamido-bridged copper(II) binuclear units [Cu(2)(oxen), oxen = N,N-bis(2-aminoethyl)oxamide] and pyridine-substituted nitronyl nitroxides (o-, m-, and p-PYNN) were synthesized and characterized structurally and magnetically. Complexes 1 and 2 are four-spin complexes. Interestingly, it is found that in complex 3, the Cu(II) ions and m-PYNN units are arranged to form 1D double-stranded helical chains, which to the best of our knowledge is the first example of a metal nitronyl nitroxide complex with such a 1D helical structure. The temperature dependencies of the magnetic susceptibilities of 1 and 2 were fitted to the four-spin model with the Hamiltonian H = -2Js(Cu1)s(Cu2) - 2j(s(Cu1)s(rad1) - s(Cu2)s(rad2)), leading to J = -150.5 cm(-)(1) and j = 47.2 cm(-)(1) for complex 1 and J = -191.7 cm(-)(1) and j = -18.9 cm(-)(1) for complex 2. The temperature dependence of the magnetic susceptibility of complex 3 was approximately simulated with a simple model composed of a dimer of Cu(II) ions and two m-PYNN molecules. The best fitting leads to the values of J = -183.0 cm(-)(1) and zJ' = -0.55 cm(-)(1) for the magnetic exchange of two Cu(II) ions through the oxamide bridge and that between the dimer of Cu(II) ions and two m-PYNN molecules, respectively. The antiferromagnetic exchange of oxamido-bridged Cu(II) ions in complexes 1-3 is strong. The strength of such antiferromagnetic interactions is also similar for the three complexes.     

新型过渡金属配合物合成,磁性和生物活性

报道９种新的过渡金属［Ｃｒ（Ⅲ）、Ｍｎ（Ⅱ）、Ｆｅ（Ⅲ）、Ｃｏ（Ⅱ）、Ｎｉ（Ⅱ）、Ｃｕ（Ⅱ）、Ｚｎ（Ⅱ）］五苯并咪唑甲基二乙三胺双核配合物的研究。变温磁化率分析结果表明，双核离子间存在反铁磁相互作用。对于二价过渡金属离子，磁交换作用大小为．对配合物进行了体外抗癌活性和农药活性测定，发现部分配合物具有生物活性。     

以氯醌酸二价阴离子为桥联配体的Fe(Ⅲ)-Fe(Ⅲ)和Mn(Ⅱ)-Mn(Ⅱ)双核配合物的合成与磁性

Two new binuclear Fe(Ⅲ)-Fe(Ⅲ) and Mn(Ⅱ)-Mn(Ⅱ) complexes containing the dianions of chloranilic acids (CA) which act as bridging ligand in the complexes, have been synthesized namely [Fe₂(phen)₄(u-CA)](ClO₄)₄·2H₂O and [Mn₂(phen)₄(u-CA)](ClO₄)₂·3H₂O (phen = O-phenanthroline; CA = dianions of chloranilic acids). They have been characterized by elemental analyses, IR, electronic spectra, susceptibility and variable-temperature magnetic susceptibility. The results indicate that there is a antiferromagnetic interaction between metal ions in the complexes at low temperature. The observed data were well fitted to those from a Heisenberg model. The obtained parameters: J= -2.02cm^-1, g = 2.25 for Fe(Ⅲ)-Fe(Ⅲ) complex; J=-5.45cm^-1, g = 2.01 for Mn(Ⅱ)-Mn(Ⅱ) complex.