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Huang Y.-J.,Hangzhou Normal University | Zhang X.-H.,Zhejiang University | Hua Z.-J.,Inspection and Quarantine Technology Center | Chen S.-L.,Hangzhou Normal University | Qi G.-R.,Zhejiang University
Macromolecular Chemistry and Physics | Year: 2010

Highly active CaCl2-modified Zn-Co(III) DMCs were prepared. XRD results showed that the modified catalyst Ca-DMC containing 0.14 wt.-% CaCl 2 was amorphous. A higher polymer yield (>61 kg polymer/g catalyst) and a shorter induction period for ROP of PO were observed for Ca- DMC than for unmodified DMC catalysts. An initiator had an inhibitory effect on the initiation and polymerization rate of PO ROP. As the molar ratio of the initiator functionality to the catalyst was increased, the reaction rate and polymer yield decreased, whereas the induction period increased. An increase in reaction temperature tended to reduce the polymer yield and broaden the MWD. The 13C NMR spectrum for an oligomer from a model polymerization without an initiator revealed that the main terminal unit of the polymer was -CH 2CH(CH3)OH because H2O in the system participated in reaction initiation. Cl- and t-BuOH may also initiate the reaction according to the small amounts of terminal -CH2Cl and -OC(CH3)3 units observed by 13C NMR spectroscopy. On the basis of common characteristics and some new evidence for DMC catalysis, a mechanism similar to a classical coordination insertion process is proposed. © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source


He Q.,Inspection and Quarantine Technology Center
Se pu = Chinese journal of chromatography / Zhongguo hua xue hui | Year: 2010

An ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/ MS) method was developed for the determination of altenuene (ALT), alternariol (AOH), tentoxin and alternariol monomethyl ether (AME) in apple juice concentrate (AJC). The sample was diluted with water, and then cleaned up with a PS DVB column. The quantification was carried out using an external standard method. The UPLC was performed on a BEH C18 column (50 mm x 2.1 mm, 1.7 microm) using a gradient elution of acetonitrile and water. The MS/MS was performed with multiple reaction monitoring (MRM) mode. The limits of quantification of the four Alternaria toxins were between 1.0 and 5.0 microg/L. The recoveries were 77.8%-117.2% with the relative standard deviations less than 9.7%. The method is sensitive, stable and reliable. It's suitable for the quantitative and qualitative analyses of the four Alternaria toxins in AJC. Source


Zhang J.,Inspection and Quarantine Technology Center
Se pu = Chinese journal of chromatography / Zhongguo hua xue hui | Year: 2011

A high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/ MS) method was established for the determination of spinosyns A and D residues in foodstuffs. The food samples were extracted with acetonitrile-water (50:50, v/v), and then purified by an HLB solid phase extraction (SPE) column. The analytes were determined by HPLC-MS/MS and quantified by external standard method. The mass spectrometric detection was operated with electrospray in positive ionization mode and the spinosyns A and D were identified in multiple reaction monitoring (MRM) mode. The linear range of the method was 1-20 microg/L, with the correlation coefficient (r2) of 0.999 9. No significant matrix effect was found for spiked samples. The recoveries of spinosyns A and D spiked in food were 76.2%-114.0% at the spiked levels of 1-10 microg/kg. The relative standard deviations (RSDs) were less than 10%. The limits of detection (LODs) and quantification (LOQs) were 0.2 microg/kg and 0.5 microg/kg for spinosyn A, 0.5 microg/kg and 1.0 microg/kg for spinosyn D, respectively. The proposed procedure was applied to the analysis of 969 real samples from Xiamen, Fujian Province (China), of which 15 positive samples were found. The results showed that the proposed method is sensitive and accurate for the determination of spinosyns A and D in foodstuffs. Source


Gao F.,Fujian Agriculture and forestry University | Chang F.,Fujian Agriculture and forestry University | Shen J.,Inspection and Quarantine Technology Center | Shi F.,Fujian Agriculture and forestry University | And 2 more authors.
Archives of Virology | Year: 2014

The complete sequence of GF_YL20, a potato virus Y (PVY) isolate from China, encodes a polyprotein of 3,061 amino acids. Sequence analysis indicates that GF_YL20 has a genomic structure different from previously reported PVY strains. It shares 99 % nucleotide sequence identity with PB209 (PVYN:O) except in VPg, but more than 97 % nucleotide sequence identity with the VPg of Mont (PVYN), PB312 (PVYNTN) and HN2 (SYR-I). Phylogenetic analysis indicates that GF_YL20 is a novel N:O recombinant with three recombination breakpoints. © 2014, Springer-Verlag Wien. Source


Fang E.,Inspection and Quarantine Technology Center | Zhang Z.,Inspection and Quarantine Technology Center | Chen X.,Xiamen University
Analytical Chemistry | Year: 2015

By coupling thin-film microextraction (TFME) with surface-enhanced Raman scattering (SERS), a facile method was developed for the determination of sulfur dioxide (SO2), the most effective food additive in winemaking technology. The TFME substrate was made by free settling of sea urchin-like ZnO nanomaterials on a glass sheet. The headspace sampling (HS) procedure for SO2 was performed in a simple homemade device, and then the SO2 was determined using SERS after uniformly dropping or spraying a SERS-active substrate (gold nanoparticles, AuNPs) onto the surface of the TFME substrate. A reproducible and strong SERS response of the SO2 absorbed onto the ZnO substrate was obtained. After condition optimization, the SERS signal intensity at a shift of 600 cm-1 and the SO2 concentration showed a good linearity in the range of 1-200 μg/mL, and the linear correlation coefficient was 0.992. The detection limit for SO2 was found to be 0.1 μg/mL. The HS-TFME-SERS method was applied for the determination of SO2 in wine, and the results obtained agreed very well with those obtained using the traditional distillation and titration method. Analysis of variance and Student t test show that there is no significant difference between the two methods, indicating that the newly developed method is fast, convenient, sensitive and has selective characteristics in the determination of SO2 in wine. © 2014 American Chemical Society. Source

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