Sample records for biureas
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Wang, Ya; Wang, Junsu; Xiang, Lu; Xi, Cunxian; Chen, Dongdong; Peng, Tao; Wang, Guomin; Mu, Zhaode
2014-05-01
A novel method was established for the determination and identification of biurea in flour and its products using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The biurea was extracted with water and oxidized to azodicarbonamide by potassium permanganate. The azodicarbonamide was then derivatized using sodium p-toluene sulfinate solution. The separation was performed on a Shimpak XR-ODS II column (150 mm x 2.0 mm, 2.2 microm) using the mobile phase composed of acetonitrile and 2 mmol/L ammonium acetate aqueous solution (containing 0.2% (v/v) formic acid) with a gradient elution program. Tandem mass spectrometric detection was performed in multiple reaction monitoring (MRM) scan mode with a positive electrospray ionization (ESI(+)) source. The method used stable isotope internal standard quantitation. The calibration curve showed good linearity over the range of 1-20 000 microg/kg (R2 = 0.999 9). The limit of quantification was 5 microg/kg for biurea spiked in flour and its products. At the spiking levels of 5.0, 10.0 and 50.0 microg/kg in different matrices, the average recovery o biurea was 78.3%-108.0% with the relative standard deviations (RSDs) < or = 5.73%. The method developed is novel, reliable and sensitive with wide linear range, and can be used to determine the biurea in flour and its products.
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NASA Astrophysics Data System (ADS)
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.
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Fate of inhaled azodicarbonamide in rats
DOE Office of Scientific and Technical Information (OSTI.GOV)
Mewhinney, J.A.; Ayres, P.H.; Bechtold, W.E.
Azodicarbonamide (ADA) is widely used as a blowing agent in the manufacture of expanded foam plastics, as an aging and bleaching agent in flour, and as a bread dough conditioner. Human exposures have been reported during manufacture as well as during use. Groups of male F344/N rats were administered ADA by gavage, by intratracheal instillation, and by inhalation exposure to determine the disposition and modes of excretion of ADA and its metabolites. At 72 hr following gavage, 30% of the administered ADA was absorbed whereas following intratracheal instillation, absorption was 90%. Comparison between groups of rats exposed by inhalation tomore » ADA to achieve body burdens of 24 or 1230 micrograms showed no significant differences in modes or rates of excretion of (/sup 14/C)ADA equivalents. ADA was readily converted to biurea under physiological conditions and biurea was the only /sup 14/C-labeled compound present in excreta. (/sup 14/C)ADA equivalents were present in all examined tissues immediately after inhalation exposure, and clearance half-times on the order of 1 day were evident for all tissues investigated. Storage depots for (/sup 14/C)ADA equivalents were not observed. The rate of buildup of (/sup 14/C)ADA equivalents in blood was linearly related to the lung content as measured from rats withdrawn at selected times during a 6-hr inhalation exposure at an aerosol concentration of 25 micrograms ADA/liter. In a study extending 102 days after exposure, retention of (/sup 14/C)ADA equivalents in tissues was described by a two-component negative exponential function. The results from this study indicate that upon inhalation, ADA is rapidly converted to biurea and that biurea is then eliminated rapidly from all tissues with the majority of the elimination via the urine.« less
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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.
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Ultraviolet-gas phase and -photocatalytic synthesis from CO and NH3. [photolysis products
NASA Technical Reports Server (NTRS)
Hubbard, J. S.; Voecks, G. E.; Hobby, G. L.; Ferris, J. P.; Williams, E. A.; Nicodem, D. E.
1975-01-01
Ammonium cyanate is identified as the major product of the photolysis of gaseous NH3-CO mixtures at 206.2 or 184.9 nm. Lesser amounts of urea, biurea, biuret semicarbazide, formamide and cyanide are observed. A series of 18 reactions underlying the formation of photolysis products is presented and discussed. Photocatalytic syntheses of C-14-urea, -formamide, and -formaldehyde are carried out through irradiation of (C-14)O and NH3 in the presence of Vycor, silica gel, or volcanic ash shale surfaces. The possible contributions of the relevant reactions to the abiotic synthesis of organic nitrogen compounds on Mars, the primitive earth, and in interstellar space are examined.