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Dong F.,Chinese Academy of Agricultural Sciences | Chen X.,Chinese Academy of Agricultural Sciences | Liu X.,Chinese Academy of Agricultural Sciences | Xu J.,Chinese Academy of Agricultural Sciences | And 3 more authors.
Journal of Chromatography A | Year: 2012

The sensitive analytical method using quick, easy, cheap, effective, rugged, and safe (QuEChERS) procedure for simultaneous determination of five novel pyrazole fungicides residues in cereals (rice and wheat), vegetables (cucumber, tomato, and lettuce), and fruits (apple and grape) was developed by liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). The five pyrazole fungicides (bixafen, fluxapyroxad, furametpyr, pyraclostrobin, and rabenzazole) were extracted from seven matrices using acetonitrile and subsequently cleaned up by octadecylsilane (C18) or graphitized carbon black (GCB) prior to LC-MS/MS analysis. The determination of the target compounds was achieved in less than 3.0min using an electrospray ionization source in positive mode (ESI+) for furametpyr, pyraclostrobin, and rabenzazole, while negative mode (ESI-) for bixafen and fluxapyroxad. The method showed excellent linearity (at least R2≥0.990) for all studied analytes. The limits of detection were below 3.0μgkg-1, and the limits of quantification did not exceed 9μgkg-1 in all matrices. The overall average recoveries in rice, wheat, cucumber, tomato, lettuce, apple, and grape at three levels (10, 100 and 1000μgkg-1) were ranged from 70.0% to 108% with all RSDs values less than 20.9% for all analytes. The method is demonstrated to be convenient and reliable for the routine monitoring of pyrazole fungicides in cereals, vegetables and fruits. © 2012 Elsevier B.V. Source


Lei P.,CAS Beijing National Laboratory for Molecular | Wang F.,CAS Beijing National Laboratory for Molecular | Gao X.,CAS Beijing National Laboratory for Molecular | Ding Y.,CAS Beijing National Laboratory for Molecular | And 4 more authors.
Journal of Hazardous Materials | Year: 2012

Nano titanium dioxide (TiO 2) photocatalyst is generally immobilized onto the matrix through the physical absorption, hydrogen bonding or chemical bonding, which is utilized for the application of wastewater treatment. In this research, TiO 2 nanoparticles were immobilized in polyvinyl alcohol (PVA) matrix via solution-casting combined with heat-treatment method. Structure characterization indicated that TiOC chemical bond formed via dehydration reaction between TiO 2 and PVA during the heat treatment process, and TiO 2 nanoparticles had been chemically immobilized in PVA matrix. Photodegradation results of methyl orange (MO) showed that the film with 10wt% TiO 2 and treated at 140°C for 2h exhibited a remarkable ultraviolet (UV) photocatalytic activity, approximately close to the TiO 2 slurry system. This was mainly attributed to the fixation effect by TiOC chemical bonds, which was indirectly confirmed by the slight loss of TiO 2 photocatalysts even after 25-cycle use. In addition, the good swelling ability of PVA matrix provided the MO molecules with more opportunities to fully contact with TiO 2, thus benefited the photocatalysis. This route to chemically immobilize TiO 2 nanoparticles is simple and cheap to prepare polymer/TiO 2 hybrid materials with high photocatalytic activity for multi-cycle use, which is of significance to the practical application of TiO 2 catalysts. © 2012 Elsevier B.V.. Source


Chen C.,Chinese Academy of Agricultural Sciences | Qian Y.,Chinese Academy of Agricultural Sciences | Tao C.,Chinese Institute for the Control of Agrochemicals | Li Y.,Chinese Academy of Agricultural Sciences
Food Control | Year: 2011

In the present study an effort has been made to evaluate the residues of selected insecticides (organophosphorous and pyrethroid) and fungicides (triazoles and chloronitriles) in fruits and vegetables collected from Xiamen, China, during the October 2006 to March 2009 monitoring campaign. Gas chromatography with electron capture detector (GC-ECD) was used to determine the concentrations of 22 pesticide residues among those recommended for pest treatment. Of 1135 samples (37.7%) that contained pesticide residues, pakchoi cabbage, legumes, and leaf mustard were the commodities in which pesticide residues were most frequently detected, with 17.2%, 18.9% and 17.2% of the samples exceeding the maximum residue limits (MRLs), respectively. Concerning the most frequently detected pesticide residues, cypermethrin was found in 18.7% of the samples analyzed. Data obtained were then used for estimating the potential health risks associated with the exposures to these pesticides. The estimated daily intakes (EDIs) range from 0.1% of the ADI for cyfluthrin to 2.61% of the ADI for omethoate and 0.1% of the ADI for omethoate. The most critical commodity is legumes, contributing 2.61% to the hazard index (HI). The results show that despite a high occurrence of pesticide residues in fruits and vegetables from this region, it could not be considered a serious public health problem. Nevertheless, an investigation into continuous monitoring and tighter regulation of pesticide residues in fruits and vegetables is recommended. © 2011 Elsevier Ltd. Source


Zhu Y.,Chinese Academy of Agricultural Sciences | Liu X.,Chinese Academy of Agricultural Sciences | Xu J.,Chinese Academy of Agricultural Sciences | Dong F.,Chinese Academy of Agricultural Sciences | And 4 more authors.
Journal of Chromatography A | Year: 2013

A modified quick, easy, cheap, effective, rugged, and safe (QuEChERS) method for the simultaneous determination of spirotetramat and its four metabolites in fruits (apple, peach) and vegetables (cabbage, tomato, potato, cucumber), based on the use of liquid extraction/partition and dispersive solid phase extraction (dispersive-SPE) followed by ultrahigh-performance chromatography coupled with tandem mass spectrometry (UHPLC-MS/MS), was established. Acidified acetonitrile (containing 1% (v/v) acetic acid) as the extraction solvent and simultaneous liquid-liquid partitioning formed by adding anhydrous magnesium sulfate (MgSO4) and anhydrous sodium acetate (NaOAc). The extract was then cleaned up by dispersive-SPE using graphitized carbon black (GCB) as selective sorbent. Further optimization of sample preparation and determination achieved recoveries of between 82 and 110% for all analytes with RSD values lower than 14% in apple, peach, cabbage, tomato, potato and cucumber at three levels (10, 100 and 1000μg/kg). The method showed excellent linearity (R2≥0.9895) for all studied analytes. The determination of the target compounds was achieved in less than 6.0min using an electrospray ionization source in positive mode (ESI+). The method is demonstrated to be convenient and reliable for the routine monitoring of spirotetramat and its metabolites in fruits and vegetables. © 2013 Elsevier B.V. Source


Chen C.,Chinese Academy of Agricultural Sciences | Qian Y.,Chinese Academy of Agricultural Sciences | Liu X.,Jiangsu Academy of Agricultural Sciences | Tao C.,Chinese Institute for the Control of Agrochemicals | And 2 more authors.
Regulatory Toxicology and Pharmacology | Year: 2012

Chlorpyrifos is a widely used organophosphorus insecticide in agricultural pest control. To understand the residue behavior of chlorpyrifos and to evaluate the dietary risk of chlorpyrifos residue in food in China, a number of residue studies were conducted on rice and cabbage. The supervised trial median residues (STMRs) for rice and cabbage were less than 0.010 and 0.227mgkg -1, respectively. Only 7.4% and 13.3% of acceptable daily intake (ADI) (0-0.01mgkg -1bw) of chlorpyrifos is occupied by dietary daily intake to the Chinese adult and children, respectively, due to the consumption of rice and cabbage. These results on risk assessment were consistent with that of JMPR. Incorporation of market survey residue data gave a 5-fold reduction in the estimated exposures to chlorpyrifos. Concerning the acute exposure, the national estimated short-term intake (NESTI) represents 0.077% and 10.6% for rice and cabbage, respectively, of the acute reference dose (ARfD) (0-0.1mgkg -1bw). The application of chlorpyrifos at the recommended dose on rice and cabbage is unlikely to pose any public health issues if it is applied according to the good agricultural practices (GAPs) established by each country. © 2011 Elsevier Inc. Source

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