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Sample records for biureas

  1. The determination of biurea: A novel method to discriminate between nitrofurazone and azodicarbonamide use in food products

    Energy Technology Data Exchange (ETDEWEB)

    Mulder, P.P.J. [RIKILT-Institute of Food Safety, Bornsesteeg 45, Wageningen (Netherlands)]. E-mail: Patrick.Mulder@wur.nl; Beumer, B. [RIKILT-Institute of Food Safety, Bornsesteeg 45, Wageningen (Netherlands); Rhijn, J.A. van [RIKILT-Institute of Food Safety, Bornsesteeg 45, Wageningen (Netherlands)

    2007-03-14

    Recently doubts have arisen on the usefulness of semicarbazide as marker residue for the illegal use of the antibiotic nitrofurazone (NFZ) in aquaculture and poultry production. Most notably azodicarbonamide (ADC) has been implicated as an alternative source of semicarbazide. ADC is used in some countries as a dough conditioner at concentrations up to 45 mg kg{sup -1}. The use of ADC-treated flour or dough in coated or breaded food products may generate false non-compliant results in the analytical method for nitrofurazone metabolites, which is currently in use. During the dough preparation process ADC is largely reduced to biurea, which can be considered as an appropriate marker residue of ADC. Thus far no methods have been published for the determination of biurea in food commodities. Due to its polar nature it is very difficult to generate sufficient retention on conventional C{sub 18} HPLC columns. With a TSK amide HILIC type column good retention was obtained. A straightforward extraction-dilution protocol was developed. Using a mixture of dimethyl formamide and water biurea was nearly quantitatively extracted from a variety of fresh, coated and processed products. Mass spectrometric detection was performed with positive electrospray ionisation. The sensitivity and selectivity of the mass spectrometer for biurea was very good, allowing detection at concentrations as low as 10 {mu}g kg{sup -1}. However, in some extracts severe ion suppression effects was observed. To overcome the implications of ion suppression on the quantitative performance of the method an isotopically-labelled biurea internal standard was synthesized and incorporated in the method. The method developed can be used effectively in nitrofurazone analysis to eliminate the risk of false non-compliant results due to the presence of azodicarbonamide-treated components in the food product.

  2. Comparative studies by IR, Raman, and surface-enhanced Raman spectroscopy of azodicarbonamide, biurea and semicarbazide hydrochloride.

    Science.gov (United States)

    Xie, Yunfei; Li, Pei; Zhang, Jin; Wang, Heya; Qian, He; Yao, Weirong

    2013-10-01

    Azodicarbonamide is widely applied in the food industry as a new flour gluten fortifier in China, Canada, the United States, and some other countries, whose metabolites of biurea and semicarbazide hydrochloride are reaction products during baking. In this study, IR, Raman and surface-enhanced Raman scattering (SERS) spectra of azodicarbonamide, biurea, and semicarbazide hydrochloride have been studied, and vibrational bands have been assigned on the basis of density functional theory (DFT) calculations. The calculated Raman spectra were in good agreement with experimental Raman spectra. The SERS method coupled with active gold substrates has also been applied for detection of the three chemicals with pure water as solvent, with the limit of detection of this method being as low as 10 μg/mL (less than 45 μg/mL). These results showed that azodicarbonamide and its metabolites could be detected by the vibrational spectra technique, which might be applied as a powerful tool for the rapid detection on these species derived from agents added to flour.

  3. Design, synthesis, insecticidal activity, and structure-activity relationship (SAR): studies of novel triazone derivatives containing a urea bridge group based on transient receptor potential (TRP) channels.

    Science.gov (United States)

    Yang, Yan; Liu, Yuxiu; Song, Hongjian; Li, Yongqiang; Wang, Qingmin

    2016-11-01

    Numerous compounds containing urea bridge and biurea moieties are used in a variety of fields, especially as drugs and pesticides. To search for novel, environmentally benign and ecologically safe pesticides with unique modes of action, four series of novel triazone analogues containing urea, thiourea, biurea, and thiobiurea bridge, respectively, were designed and synthesized, according to various calcium ion channel inhibitors which act on transient receptor potential protein. Their structures were characterized by [Formula: see text] NMR, [Formula: see text] NMR, and HRMS. The insecticidal activities of the new compounds were obtained. The bioassay results indicated that compounds containing a thiourea bridge and a thiobiurea bridge exhibited excellent insecticidal activities against bean aphid. Specifically, compounds [Formula: see text], [Formula: see text], and [Formula: see text] exhibited 85, 90, and 95 % activities, respectively, at 10 mg/kg. Compounds [Formula: see text] (30 %), [Formula: see text] (35 %), [Formula: see text] (30 %), and [Formula: see text] (40 %) exhibited the approximate aphicidal activity of pymetrozine (30 %) at 5 mg/kg. In addition, some target compounds exhibited insecticidal activities against lepidopteran pests. From a molecular design standpoint, the information obtained in this study could help in the further design of new derivatives with improved insecticidal activities.

  4. Component Analysis of Deposits in Selective Catalytic Reduction System for Automotive Diesel Engine

    Directory of Open Access Journals (Sweden)

    Zhu Neng

    2016-01-01

    Full Text Available In this paper, deposits in exhaust pipes for automotive diesel engines were studied by various chemical analysis methods and a kind of analysis process to determine the compositions of organic matter was proposed. Firstly, the elements of the deposits were determined through the element analysis method. Then using characteristic absorption properties of organic functional groups to the infrared spectrum, the functional groups in the deposits were determined. Finally, by GC-MS (gas chromatography - mass spectrometry test, the content of each main component was determined quantitatively. Element analysis results indicated that the deposits adsorbed metal impurities from fuel oil, lubricating oil, mechanical wear and urea water solution. The result of GC-MS test showed that the area percentage of cyanuric acid was the biggest (about 85%, the second was urea (about 4%, and the content of biuret and biurea was scarce.

  5. Study on the fatty oil and total protein of processed Croton using TCM's method and Uyghur Medicine's method respectively%中维医巴豆霜脂肪油和总蛋白质的比较

    Institute of Scientific and Technical Information of China (English)

    姜林; 黄文娟

    2011-01-01

    Objective: Comparing the fatty oil component and total protein content of two different processing of Crowns. Methods: Using petioleum ether to distill the fatty oil and using GC-MS method to mensure the component; using biurea method to mensure the total proteins content. Results: The result of fatty oil content of unprocessed Croton, processed Croton using TCM's method and Uyghur medicine's method convinced 15,17, 21 kinds component and the concentration is 58.84%, 19.17%, 38.80%; the total protein concentration is 35.375, 22.395, 21.425mg/g respectively. Conclusion: After processing, the component of processed Croton has been increased, the mutual component's concentration is different; the total proteins and the fatty oil decreased sharply.%目的:研究巴豆采用中维医不同方法炮制后脂肪油及总蛋白质的变化.方法:采用石油醚冷浸法测定脂肪油含量;GC-MS法分析测定脂肪油成分;双缩脲法测定总蛋白的含量.结果:生巴豆、中医传统巴豆霜、维医巴豆霜的脂肪油含量分别为58.84%、19.17%、38.80%;GC-MS分析确认了15、17、21个成分及含量;总蛋白含量分别为35.375、22.395、21.425mg/g.结论:巴豆炮制后脂肪油的成分有所增加,共有成分含量增减不一;脂肪油和总蛋白的含量明显降低.

  6. Kinetic Analysis of the Azodicarbonamide Production Process in Gas-Liquid-Solid Systems%发泡剂ADC 生成过程动力学分析

    Institute of Scientific and Technical Information of China (English)

    林诚; 张济宇

    2001-01-01

    The oxidation of solid biurea with chlorine in aqueous solution to produce azodicarbonamide was experimentally studied in a 1 L agitated glass vessel with a four-blade paddle stirrer. Based on the film theory, a model is first developed for this system by taking the gas-liquid and solid-liquid mass transfer, solid dissolution, and instantaneous reaction between the dissolved reactants into consideration. The model can reasonably well represent the experimental data. According to the values of gas-liquid and solid-liquid mass transfer coefficients estimated with the proposed model, it is found that the gas-liquid mass transfer is a rate-controlling step in most cases, but the solid-liquid mass transfer becomes a rate-controlling step when the reaction is close to the end of this process.%在玻璃搅拌反应器中进行了固体联二脲与氯气液相氧化反应生成发泡剂 ADC过程的传质与动力学实验, 提出了基于双膜理论的数学模型,以描述这一反应系统所涉及的气液和固液传质、固体溶解以及溶解物在液相中发生瞬间反应,特别是随反应进行固体反应物粒径变小导致固液传质速率减小的复杂过程. 模型能很好地描述实验结果. 依据模型估测的气液与固液传质系数值比较表明,气相反应物氯气的溶解传质过程是影响整个过程速率的主要控制步骤.