Wang L.,Zhangzhou Entry exit Inspection and Quarantine Bureau
Se pu = Chinese journal of chromatography / Zhongguo hua xue hui | Year: 2012
A comparison was made between the two versions of QuEChERS sample preparation method for the extraction of 66 organophosphorus pesticides (OPPS) in vegetables. The two QuEChERS methods were the original method without buffer published in 2003, and the AOAC Official Method 2007. 01 with acetate buffer. The adsorption behaviors of primary secondary amine (PSA) sorbent and C18 sorbent on the OPPS were studied. The method of after-extraction addition was used to evaluate matrix effects for OPPS in matrix of broccoli, tomato, green soybean, radish and shallot during liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis. As a result, the QuEChERS method with acetate buffer gave higher and more consistent recoveries for some of OPPS. The PSA sorbent and C18 sorbent can adsorb dibrom, so the QuEChERS method was not suitable for the analysis of dibrom. The maximum matrix effects were in the extracts of broccoli during LC-MS/MS analysis. In this article, OPPS were extracted using the QuEChERS method with acetate buffer, and analysed by LC-MS/MS under the optimized conditions with monitoring 132 MS/MS transitions of precursor ions (two for each pesticide) in one single run. Recoveries for all but dibrom at fortification levels of 10, 40, 80 microg/kg in broccoli, tomato, green soybean, radish and shallot ranged from 55% to 122% with relative standard deviations of 1.6% - 18%. The limits of quantification (S/N > or = 10) were 0.1 - 8 microg/kg. Based on these results, the analytical method was proven to be highly efficient, robust and sensitive, and suitable for the monitoring of the maximum residue limits (MRLs) of 66 OPPS in vegetables.
Zhou Z.,Xiamen University |
Zhang H.,Zhangzhou Health Vocational College |
Wang G.,Zhangzhou Entry exit Inspection and Quarantine Bureau |
Zheng T.,Xiamen University
Mitochondrial DNA | Year: 2015
The complete mitochondrial genome of the Chinese lake gudgeon Sarcocheilichthys sinensis was first determined in this study. It is a circular DNA double strand of 16,684bp in length, encodes genes for 13 proteins, 2 ribosomal RNA subunits, 22 transfer RNAs and an A+T-rich control region with the typical gene order in vertebrate mitogenomes. Overall nucleotide composition is 30.5% A, 26.6% C, 16.7% G and 26.3% T. Three start codons (ATG, GTG and ATA) and three stop codons (TAG, TAA and T) were found in all protein-coding genes. The tRNA-SerAGY lacked the dihydrouridine arm and could not fold into typical cloverleaf secondary structure. The origin of L-strand replication was identified between the tRNA-Asn and tRNA-Cys genes. © 2013 Informa UK Ltd.
Zhang M.-S.,Zhangzhou Normal University |
Huang J.-R.,Zhangzhou Entry exit Inspection and Quarantine Bureau |
Zheng X.-H.,Inspection and Quarantine Technical Center |
Xie Q.-F.,Zhangzhou Normal University
Chemical Research in Chinese Universities | Year: 2011
A new liquid-liquid microextraction method based on the solidification of floating organic drops coupled with gas chromatography was developed for the determination of trace benzene, toluene and xylene(BTX) in water samples. In the microextraction procedure, a microdrop of n-decanol was delivered to the surface of the analytes' solution, and stirred for a desired time. Following the absolute extraction, the sample vial was cooled in an ice bath for 10 min. The solidified n-decanol was then transferred into a plastic tube and melted naturally; and 1 μL of it was injected into gas chromatography for analysis. Factors relevant to the extraction efficiency were studied and optimized. The optimal experimental conditions were: 15 μL of n-decanol as extractive solvent, 30 mL of solution containing analytes, no salt, the stirring rate 400 r/min, the extraction temperature 30 °C, and the extraction time 30 min. Under those optimized conditions, the detection limit(LOD) of analytes was in a range of 0.05-0.10 ng/mL by the developed method. A good linearity(r>0.99) in a calibration range of 0.01-100 μg/mL was obtained. The recoveries of the real samples at different spiked levels of BTX were in the range from 92.2% to 103.4%.
Lin W.,Zhangzhou Entry exit Inspection and Quarantine Bureau |
Lin W.,Beijing Normal University |
Cheng X.,Beijing Normal University |
Xu R.,Beijing Normal University
PLoS ONE | Year: 2011
Social-economic factors are considered as the key to understand processes contributing to biological invasions. However, there has been few quantified, statistical evidence on the relationship between economic development and biological invasion on a worldwide scale. Herein, using principal factor analysis, we investigated the relationship between biological invasion and economic development together with biodiversity for 91 economies throughout the world. Our result indicates that the prevalence of invasive species in the economies can be well predicted by economic factors (R2 = 0.733). The impact of economic factors on the occurrence of invasive species for low, lower-middle, upper-middle and high income economies are 0%, 34.3%, 46.3% and 80.8% respectively. Greenhouse gas emissions (CO2, Nitrous oxide, Methane and Other greenhouse gases) and also biodiversity have positive relationships with the global occurrence of invasive species in the economies on the global scale. The major social-economic factors that are correlated to biological invasions are different for various economies, and therefore the strategies for biological invasion prevention and control should be different. © 2011 Lin et al.
Zhang M.,Zhangzhou Normal University |
Huang J.,Zhangzhou Entry exit Inspection and Quarantine Bureau |
Zheng X.,Inspection and Quarantine Technical Center |
Wu L.,Zhangzhou Normal University
Chromatographia | Year: 2010
A novel analytical technique termed ultrasonic-assisted drop-to-drop solvent microextraction (USA-DDSME) in a capillary tube was developed to determine trace benzene, toluene, xylene in one drop of a water sample, which was combined with gas chromatography-flame ionization detection (GC-FID). The advantages of this method are rapidity, convenience, ease of operation, simplicity of the device, and extremely little solvent and sample consumption. Extraction conditions including the type of extraction solvent, the volume of extraction solvent, the volume of sample, extraction time and effect of salt concentration were optimized. The best optimum parameters for extraction were achieved with 3 μL of extraction solvent. Chloroform was divided into four equal divisions in 20 μL water sample (without salt addition) in a capillary tube and ultrasonicated for 10 min, centrifugated at 2,500 rpm for 5 min to let the extraction solvent settle at the bottom of the capillary tube, then 1 μL of the separated extraction solvent was injected into the GC-FID for analysis. Linearity of the method was determined by analyzing spiked water samples over a concentration range of 0.1-50 μg mL-1. Correspondingly, the LOD values were 0.01 μg mL-1. All calibration curves were found to have good linearity with correlation coefficients (r 2) > 0.995. The precision (RSD) of the system, measured by six repeated determinations of the analytes at 1 μg mL-1 were in the range of 1.6-3.5%. © 2010 Vieweg+Teubner Verlag | Springer Fachmedien Wiesbaden GmbH.