WorldWideScience

Sample records for biureas

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

    Science.gov (United States)

    Mulder, P P J; Beumer, B; Van Rhijn, J A

    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(-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 C18 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 microg kg(-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. PMID:17386736

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

    International Nuclear Information System (INIS)

    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-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 C18 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 μg kg-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

  3. 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.

  4. 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.