Time filter

Source Type

Wang S.,Yanshan University | Di N.,Qinhuangdao Entry Exit Inspection and Quarantine Bureau | Song J.,Yanshan University
Advanced Materials Research | Year: 2013

Increasing use of pyrethroid insecticides in tidal farms has resulted in the severe pollution of coastal water environment and sedimentary environment. In this work, the migration and transformation of three pyrethroid insecticides, fenpropathrin, cypermethrin and deltamethrin in Bohai coastal zone were studied. The results showed that the adsorption of pyrethroids on the coastal sediments matched pseudo-second-order kinetics and the chemical adsorption played a major role. The degradation of three pyrethroids included chemical degradation and biological degradation. The chemical degradation had predominance function at the initial 14 hours, but the biological degradation effect was increasing continuously in the transformation process, so that the proportion of biological degradation in total degradation reached about 68% at 110h. M-phenoxyphenyl-acetonitril was identified as the stable degradation product by GC-MS. © (2013) Trans Tech Publications, Switzerland.

Luo J.,China Agricultural University | Song J.-H.,Beijing Laboratory of Food Quality and Safety | Pang R.-P.,Qinhuangdao Entry Exit Inspection and Quarantine Bureau | Ren F.-Z.,China Agricultural University
Guang Pu Xue Yu Guang Pu Fen Xi/Spectroscopy and Spectral Analysis | Year: 2016

Different breeds of cows affect the form of fat exist in dairy products and the final functionality, which depended mainly on the composition of the milk fat globules(MFG). However, the relationship between the composition and breeds has not been illuminated. In our study, differences in the lipid content and fatty acid composition of native bovine, buffalo and yak MFG were investigated by confocal Raman spectroscopy. The research offers the possibility of acquisition and analysis of the Raman signal without disruption of the structure of fat globule. The results showed that yak MFG had a higher ratio of band intensities at 2 885/2 850 cm-1, indicating yak MFG tend to have a triglyceride core in a fluid state with a milk fat globule membrane in a crystalline state. The buffalo and yak MFG had a higher level of unsaturation compared to bovine MFG, shown by a higher ratio of band intensities at 1 655/1 744 cm-1. The results indicate that small MFG of buffalo is more unsaturated than yak, while the large MFG of buffalo is less unsaturated than the yak. Thus, selective use of cream with yak MFG would allow a harder and more costly churning process but lead to a softer butter. Buffalo milk which contains larger MFG is more suitable for cream and MFG membrane separation. © 2016, Science Press. All right reserved.

Ding S.,Northeastern University China | Zhao X.,Qinhuangdao Entry Exit Inspection and Quarantine Bureau
2011 IEEE 3rd International Conference on Communication Software and Networks, ICCSN 2011 | Year: 2011

The key problem in P2P network is effectively to locate resources. Chord has been widely used as a routing protocol in structured P2P networks, but there is a lot of redundant information in the node's finger table. By analyzing Chord protocol, an improved Chord algorithm is proposed in this paper. Analysis on theory and simulation results show that the improved finger tables reduce redundancy and improved Chord algorithm has better performance. © 2011 IEEE.

Yu L.,Hebei University | Cao Y.,Qinhuangdao Entry Exit Inspection and Quarantine Bureau | Zhang J.,Qinhuangdao Entry Exit Inspection and Quarantine Bureau | Cui Z.,Qinhuangdao Entry Exit Inspection and Quarantine Bureau | Sun H.,Hebei University
Food Additives and Contaminants - Part A Chemistry, Analysis, Control, Exposure and Risk Assessment | Year: 2012

Medicinal herbs have a very important role in health protection and disease control, and have been used in health foods. Polycyclic aromatic hydrocarbons (PAHs) have carcinogenic, biological and mutagenic effects. In this paper, the content of 16 PAHs as representative contaminants in nine Chinese medicinal herbs, as additives for health foods, was investigated in order to ensure food safety from this source. A highly sensitive isotope dilution-gas chromatography-tandem mass spectrometry (ID-GC-MS/MS) method combined with gel permeation chromatography (GPC) and solid-phase extraction (SPE) was developed. Calibration curves showed good linearity for all PAHs (R2> 0.999), and the limit of quantification (LOQ) ranged from 0.42 to 2.7 μg kg-1. Average recoveries for these compounds were in the range of 52.5-117%, 52.6-119% and 81.4-108% at the concentrations of 10, 50 and 250 μg kg-1 with RSD of 1.8-15%, 0.9-15% and 1.0-15%, respectively. The proposed method was used for the analysis of nine Chinese medicinal herbs. Total levels of PAHs varied from 98.2 μg kg-1 (cassia seed) to 2245 μg kg-1 (eucommia bark). The highest level was found for phenanthrene (Phe) in liquorice root (631.3 μg kg-1), indigowoad leaf (551.0 μg kg-1), rose flower (435.2 μg kg-1) and eucommia bark (432.3 μg kg-1). The proposed method could provide a useful basis for safety monitoring of herbs and risk management for PAHs in the health food industry. © 2012 Copyright Taylor and Francis Group, LLC.

Pang G.-F.,Chinese Academy of Inspection and Quarantine | Fan C.-L.,Chinese Academy of Inspection and Quarantine | Zhang F.,Chinese Academy of Inspection and Quarantine | Li Y.,Chinese Academy of Inspection and Quarantine | And 7 more authors.
Journal of AOAC International | Year: 2011

An efficient and sensitive method has been established for simultaneous determination of 653 pesticides in teas by GC/MS and HPLC/MS/MS. The method involved extraction with acetonitrile followed by cleanup using Cleanert-TPT SPE and subsequent identification and quantitation of 490 pesticides by GC/MS and 448 pesticides by HPLC/MS/ MS. The LODs for pesticides determined by GC/MS were between 1.0 and 500 μg/kg, and those determined by HPLC/MS/MS were between 0.03 and 4820 μg/kg. At the low fortification levels of 0.01-100 μg/kg, the average recoveries of 94% of the pesticides determined by GC/MS were between 60 and 120%, 77% of which had an RSD below 20%. For 91% of pesticides determined by HPLC/MS/MS, the average recoveries were between 60 and 120%, 76% of which had an RSD below 20%. The paper also reports a novel SPE column, Cleanert TPT, which comprised graphitized carbon black (PestiCarb), polyamine silica, and amide polystyrene for purifying the tea samples. The results indicated good repeatiblity and reproducibility. © 2012 Publishing Technology.

Discover hidden collaborations