Polymeric Nitrofuran Derivatives. I. Radical-Initiated Homo- and Copolymerization of 5-Nitrofurfuryl Methacrylate

The radical homopolymerization of 5-nitrofurfuryl methacrylate (NFMA) and the copolymerization of NFMA with methyl methacrylate and various vinyl monomers, respectively, have been studied in dimethylformamide at 65°C. NFMA and poly(NFMA) have been characterized by ¹H-NMR, IR, and UV spectroscopy. The influence of polymerization conditions on monomer conversion and on the molecular weight of the polymers obtained has been investigated. The thermal behavior of the polymers obtained has been studied by TGA and DSC analysis.     

酰腙键聚合物凝胶的制备及其在硝基呋喃类药物分析中的应用

以1,3,5-苯三甲酰肼和间苯二甲醛为有机单体,利用席夫碱反应原理和酰腙共价键为交联点,通过一步交联聚合法研制了一种新型酰腙键聚合物凝胶。采用扫描电子显微镜、红外光谱、固体核磁和热重分析对所制备的聚合物凝胶进行结构和形貌表征,结果表明材料具有良好的物化性能。将其作为固相萃取吸附剂,结合高效液相色谱-二极管阵列检测器检测,建立了饲料中4种硝基呋喃类药物的分析方法。通过单因素实验,系统考察了吸附剂用量、上样体积、洗脱溶剂和洗脱体积对方法回收率的影响。在最优实验条件下,呋喃它酮（FTD）、呋喃西林（NFZ）、呋喃妥因（NFT）和呋喃唑酮（FZD）在1.0～200μg/L范围内线性关系良好,相关系数（r）均大于0.9990,方法的检出限以信噪比（S/N=3）计算为0.1～0.5μg/L,定量限（S/N=10）为1.0～5.0μg/L,在3个浓度水平（10、50和100μg/L）加标下样品的回收率在78.5%～96.8%之间,相对标准偏差（RSD）为2.1%～9.3%。该方法的检出限低、灵敏高,可用于饲料样品中硝基呋喃类药物的灵敏准确分析。     

高效液相色谱-串联质谱联用测定蜂王浆中的四种硝基呋喃类药物的代谢物

报道了高效液相色谱-串联质谱联用测定蜂王浆中呋喃唑酮、呋喃西林、呋喃妥因和呋喃它酮4种硝基呋喃类药物的代谢物残留的方法。以三氯乙酸作为蜂王浆的蛋白质沉淀剂,同时提供衍生化反应所需的酸性环境;使用4种同位素内标,补偿了衍生化效率、衍生后样品溶液的pH值及光照对定量结果所产生的影响,极大地提高了定量的准确性。实验结果表明,呋喃它酮代谢物的检测下限可以达到0.03 μg/kg,其他3种硝基呋喃类药物的代谢物的检测下限可以达到0.05 μg/kg（S/N大于5）;呋喃它酮代谢物的定量下限可以达到0.20 μg/kg,其他3种硝基呋喃类药物的代谢物的定量下限可以达到0.25 μg/kg（S/N大于10）;线性范围为0.4~20 ng/mL,添加回收率为97.7%~104.8%(内标校正),相对标准偏差（RSD）为2.7%~9.7%。     

Polyfluoroalkyl Derivatives of Nitrogen. XLI [1], Cross-linking of a Nitroso Rubber Using Perfluoro-2,5-diazahexane-2,5-dioxyl and Its Derivatives

Perfluoro- 2,5-diazahexane- 2,5-dioxyl and a polymeric product resulting from its reaction with trifluoronitrosomethane have been used to cross-link elastomeric copolymers prepared from trifluoronitrosomethane, tetrafluoroethylene, and hexafluorobuta- 1,3-diene. The dioxyl, a diradical, is an effective vulcanizing agent at room temperature, and its polymeric derivative is similarly useful at elevated temperatures, presumably via in situ formation of diradicals which effect cross-linking. The thermal stabilities of the vulcanizates obtained are very similar to those of the raw elastomers.     

Functional Polymers. L Terpolymers of 10-Undecenoate Derivatives with Ethylene and Propylene

Terpolymers of 2,6-dimethylphenyl 10-undecenoate with ethylene and propylene have been synthesized. With titanium-based coordination initiator systems, a crystalline terpolymer was obtained which consists of blocks of ethylene and propylene, indicated by two distinct melting transitions. With vanadium-based systems, an amorphous ethylene/ propylene terpolymer was obtained. The crystalline terpolymer was hydrolyzed to the sodium carboxylate salt, which was acidified to give the polymeric carboxylic acid. All polymers were characterized by their infrared,¹H-, and ¹³C-NMR spectra, by differential scanning caiorim-etry, elemental analysis, and dilute-solution viscometry. In addition the polymeric sodium salt was characterized by wide-angle x-ray diffraction.     

有效合成5—硝基呋喃烯衍生物

报道了一种有效合成５－硝基呋喃烯衍生物的方法。在常温、弱碱Ｋ２ＣＯ３存在下（ｔｒａｃｅＨ２Ｏ），５－硝基呋喃亚甲基溴化钾盐与芳醛反应，高产率、高立体选择性地得到５－硝基呋喃烯衍生物。     

The assay of antibiotics in pharmaceutical preparations using reverse-phase HPLC

Chromatographic methods are presented for the determination of chloramphenicol, erythromycin, tyrothricin, nystatin, penicillin, streptomycin, sulphanilamides and nitrofurans, in some pharmaceutical formulations. The methods have been applied in routine analysis and are in general capable of distinguishing the main antibiotic from decomposition products and likely congeners.     

How can zero tolerances be controlled? The case study of Nitrofurans

Nitrofurans comprise a group of antibiotic substances that have been used widely in the past in intensive farming of pigs, poultry, fishes, and shrimps. Studies in the late 1980s and early 1990s have proven that they are metabolised shortly after administration and form persistent residues that could be detected in the tissues of treated animals for weeks after administration. Both the nitrofurans as well as special metabolites have been classified as genotoxic compounds. No maximum residue limit (MRL) could be fixed either due to a lack of data or because the toxicological data did not support the derivation of an acceptable daily intake (ADI). Therefore, nitrofurans are listed in Annex IV of Council Regulation EEC No. 2377/90. From a regulatory point of view, any exposure to those substances is deemed a hazard to human health. Consequently Annex IV substances are controlled with zero tolerances. Electronic Supplementary Material Supplementary material is available for this article at Presented at AOAC Europe / Eurachem Symposium March 2005, Brussels, Belgium.     

Water-Soluble Polymeric Methanofullerene and Fulleropyrrolidine Derivatives

Water-soluble methanofullerene and fulleropyrrolidine derivatives were synthesized by the reactions of methanofullerenes (MFs) and fulleropyrrolidines (FPs) with poly(N-vinylpyrrolidone) (PVP) bearing one terminal amino group. The products contain MF or FP covalently bound to the polymer, corresponding polymeric complexes, and unreacted PVP. Large aggregates of the polymeric MF and FP derivatives are found in aqueous solutions. The electrooptical properties of the products differ considerably from those of the initial polymer. The phosphorus-containing MF and FP derivatives are capable of cleaving the molecule of plasmid DNA.     

Computer simulation of polymeric materials. I. Stress-strain behavior

A model of polymeric materials has been developed that includes many of the features of condensed-phase polymer chain dynamics, central among them chain relaxation via conformational motion. The model consists of a number of chains of particles that are connected by bonds with multiwelled potentials to approximate the energetics of conformational motion. Interactions between particles on adjacent chains are modeled by short range repulsive potentials. We have examined the stress-strain behavior of the model using molecular dynamics simulations and find qualitative agreement with the observed experimental behavior of polymeric materials.     

联萘衍生物作为手性配体在二烷基锌和醛不对称加成反应中的应用

光学活性的联萘衍生物作为优异的手性配体应用到不对称催化中已取得了巨大进展,显示出广阔的应用前景,综述了近年来联萘衍生物小分子、树枝状大分子和高分子作为手性配体和其金属络合物作为手性催化剂在二烷基锌和醛不对称加成反应中的应用.     

Broad specificity indirect competitive immunoassay for determination of nitrofurans in animal feeds

A generic hapten of nitrofurans was synthesized by derivatization of 5-nitrofurfural with diamine, and the hapten was coupled to carrier protein to prepare different immunogens and coating antigens by using diazotization method and glutaraldehyde method. The obtained novel polyclonal antibodies from immunized rabbits showed broad cross reactivity among seven nitrofurans. After assessment of four coating antigen/antibody combinations, an indirect competitive immunoassay was developed to simultaneously detect the seven nitrofurans in animal feeds. The limits of detection for these analytes were in the range of 5-16 μg kg⁻¹ depending on the compound. Recoveries from nitrofurans fortified blank feeds at levels of 30 and 100 ng g ⁻¹ were in a range of 82.6-108.4% with coefficients of variation lower than 11.4%. The immunoassay was further validated by a HPLC method and the two methods showed good correlation (r = 0.9924). Therefore, the proposed immunoassay could be used as a practical method to monitor the illicit use of nitrofurans in animal feeds.     

Polymers for tissue engineering,medical devices,and regenerative medicine. Concise general review of recent studies

Recently investigated applications of polymeric materials for tissue engineering, regenerative medicine, implants, stents, and medical devices are described in the present review. Papers published during the last 2 years about polymeric materials used for preparation of various polymeric scaffolds, methods of fabrication of such scaffolds and their effectiveness in providing support for cell growth and development into various tissues and enhancing or mimicking an extracellular network (ECM's) have been cited. Papers describing the use of such polymeric materials for tissue engineering of cartilage and bones were cited. The exciting developments in the field of regenerative medicine, based on application of the self‐assembled biocompatible polymeric scaffolds for regeneration of tissues and organs are described in some detail. The use of the biocompatible and biodegradable collapsible polymeric stents, as well as the use of biocompatible, but not necessarily biodegradable polymeric materials for protective coatings of metallic stents and reservoirs of drugs, preventing restenosis and other post‐operative complications that may occur after insertion of a stent, have been reviewed. Clinical results pointing out the advantages of such treatments, as well as results indicating their limitations, have been cited. New formulas, for coating implants, stents, and other medical devices, have been discussed. Copyright © 2006 John Wiley & Sons, Ltd.     

An ESI‐MS and NMR Study of the Self‐Assembly of Guanosine Derivatives

The self‐assembly of guanosine (G) derivatives in the presence of alkali‐metal ions gives octameric or polymeric aggregates composed of stacked G quartets. This process is studied for some lipophilic G derivatives by means of ESI‐MS. The ESI‐MS results are discussed in the light of complementary information obtained from NMR and SANS (small‐angle neutron scattering) studies. ESI‐MS gives an excellent picture of the self‐assembly process and gives new information on the effect of different cations and anions on the dimensions of the assembled species, information that could not have been obtained with SANS and NMR alone.     

Synthesis of Thiourea Derivatives on Soluble Polymeric Support

A modified poly(ethylene glycol) (PEG) has been developed as the soluble polymeric supports for liquid phase synthesis of novel thiourea derivatives.In each step of the sequence,the PEG-bound products were precipitated in cold Et2O and the unreacted materials and by-products were removed by simple filtration.The progress of reaction,purity of the isolation and the structure of the PEG-bound products were easily monitored by TLC,IR and ^1H NMR spectra.Representative thiourea derivatives were obtained in moderate yields with excellent purity from this modified PEG-bound product by the cleavage with 50% TFA/H2O.     

Screening method for the detection of a range of nitrofurans in avian eyes by optical biosensor

An immunobiosensor assay was developed for the multi-residue screening of a range of nitrofuran compounds in avian eyes. A polyclonal antibody which binds at least 5 of the major parent nitrofurans was raised in a rabbit after inoculation with a nitrofuran mimic-protein conjugate. Sample homogenates were extracted into 0.1M hydrochloric acid and subjected to clean-up by solid phase extraction and micro-centrifugation prior to biosensor analysis. Validation data obtained from the analysis of 21 fortified samples has shown that the method has a detection capability (CCβ) of less than 1 ng eye(-1) for nitrofurazone (NFZ). In addition, cross-reactivity data and the analysis of a smaller number of fortified samples have shown that the method will also detect a range of other major parent nitrofurans including furazolidone (FZD), furaltadone (FTD), nitrofurantoin (NFA) and nifursol (NFS). Intra-assay variation (n=10) was calculated at 12.9% and 10.1% at concentrations of 1 ng eye(-1) and 2 ng eye(-1) NFZ respectively. Inter-assay variation (n=3) was determined to be 10.8% and 4.7% at the same NFZ concentrations respectively. The cross-reactivity profile and validation data for the detection of these nitrofurans are presented together with the results obtained following the analysis of a small number of incurred samples using the developed method.     

Construction of Extended and Polymeric 1,3-Dithiolane and Tetrathiafulvalene Derivatives using Cycloaddition of Bun 3P.CS2

Abstract

Cycloaddition of the adduct between Buⁿ ₃P and CS₂ to strained double bonds such as in norbornene gives novel zwitterionic products such as 5. This dissociates to the ylide 4 so that carrying out the reaction in the presence of an aldehyde leads to a Wittig reaction to give 2-alkylidene-1,3-dithiolanes. The compound 5 reacts with acetylenic dipolarophiles by cycloaddition accompanied by loss of Buⁿ ₃P to give dihydro-TTF derivatives. Both these reaction types also occur for norbornadiene and by using this together with dialdehydes or diacetylenes a range of new sulfur-rich extended and polymeric structures have been obtained.     

Bile Acid Derivatives in the Preparation of New Synthetic Polymers

Bile acids are compounds stored in the gallbladder and help in the digestion of fats and lipids in the gastro-intestinal tract. These amphiphilic compounds can interact favorably with both hydrophilic and hydrophobic molecules. To improve the biocompatibility of the polymers used in biomedical and pharmaceutical applications, we have synthesized various derivatives of bile acids and used them in the preparation of new polymeric materials, including both polyaddition and polycondensation products. The use of the bile acid derivatives should improve the biocompatibility of the polymers, especially when they are used in the gastrointestinal tract. Even in case of decomposition, these derivatives are not expected to cause serious problems of toxicity. We have used bile acids in the preparation of both stable polymers (hydrogels) and degradable ones (polyanhydrides).     

Stereochemistry of new nitrogen containing heterocyclic compounds.; X. Supramolecular structures and stereochemical versatility of polymeric complexes

New polymeric complexes of Cu(II), Co(II), Ni(II) and UO2(II) with 5-(2(1)-carboxyphenylazo)-8-hydroxyquinoline (LH2) have been prepared and characterized on the basis of analytical, magnetic, 1H NMR, EPR and electronic spectral studies. Tentative structures for the polymeric complexes are proposed. The important infrared (IR) bands and the main 1H NMR signals are assigned and discussed relative to the molecular structure. EPR spectrum of copper(II) complex has been studied with a view to assigning their stereochemistries. Various EPR parameters have been calculated. Each metal has six-coordinates in an octahedral environment. The ligand acts as a dibasic (bis-bidentate chelating agent coordinating through CN, N=N, COOH and OH groups by replacement of a proton from the two latter groups. Considerable interest has also been focused on the synthesis of the azo compounds and its polymeric metal complex due to its wide potential applications. The thermal decomposition behavior of the complexes is also discussed.     

Dynamic Covalent Chemistry: A Facile Room‐Temperature,Reversible, Diels–Alder Reaction between Anthracene Derivatives and N‐Phenyltriazolinedione

A series of readily accessible, dynamic Diels–Alder reactions that are reversible at room temperature have been developed between anthracene derivatives as dienes and N‐phenyl‐1,2,4‐triazoline‐3,5‐dione as the dienophile. The adducts formed undergo reversible component exchange to form dynamic libraries of equilibrating cycloadducts. Furthermore, reversible adduct formation allows temperature‐dependent modulation of the fluorescent properties of anthracene components; a feature of potential interest for the design of optodynamic polymeric materials by careful selection and manipulation of these simple dienes and dienophiles.