Wei Li

Publications (31)58.39 Total impact

• Article: Transplantation of bone marrow-derived endothelial progenitor cells attenuates cerebral ischemia and reperfusion injury by inhibiting neuronal apoptosis, oxidative stress and nuclear factor-κB expression.

  Jing Qiu, Wei Li, Shuhang Feng, Min Wang, Zhiyi He
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  ABSTRACT: The aim of the present study was to investigate the neuroprotective effects of bone marrow-derived endothelial progenitor cell (EPC) transplantation against cerebral ischemia/reperfusion (I/R) injury in rats and to delineate the possible underlying mechanisms. Cerebral I/R injury was established by 2 h of middle cerebral artery occlusion (MCAO) followed by reperfusion for 24 h. EPCs were isolated from bone marrow of the donor rats, grown in conditioned medium, and characterized by flow cytometry analysis of several surface markers. Labeled EPCs (106 cells) were infused into rats at the onset of reperfusion and 12 h after reperfusion via the tail vein. Infarct volume was assessed at 24 h after reperfusion by using triphenyltetrazolium chloride (TTC) staining. The expression of cell apoptosis-related proteins including Bcl-2 and Bax was determined by western blot analysis, and the activity of caspase-3 was also measured. We evaluated the activities of some antioxidative enzymes, such as superoxide dismutase (SOD), glutathione peroxidase (GSH-PX), the non-enzymatic scavenger glutathione (GSH) and detected the content of malondialdehyde (MDA) in the ischemic penumbra. Moreover, the expression of nuclear factor-κB (NF-κB) in the ischemic regions of rats was examined by immunohistochemical staining and western blot analysis. The results showed that transplantation of EPCs significantly reduced the cerebral infarct volume, decreased caspase-3 activity, upregulated Bcl-2 expression, and downregulated the expression of Bax and NF-κB. Furthermore, reduced levels of MDA, significantly elevated activities of SOD and GSH as well as GSH-PX were also found in I/R rats transplanted with EPCs. Collectively, our data demonstrated that transplantation of bone marrow-derived EPCs exerts potent neuroprotective functions against cerebral I/R injury in rats, and the protective effects may be associated with its antioxidative and anti-apoptotic properties.
  International Journal of Molecular Medicine 11/2012; · 1.98 Impact Factor
• Article: Metabonomic responses in rat urine following subacute exposure to propoxur.

  Yu-Jie Liang, Hui-Ping Wang, Lin Yang, Wei Li, Yi-Jun Wu
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  ABSTRACT: Metabolic profiling of urine from pesticide-treated rats was investigated by the nuclear magnetic resonance (NMR)-based metabonomic strategy. Twenty-four-hour urine samples of rats were collected after administration with propoxur at doses of 0.85, 1.70, and 8.51 mg/kg, respectively, for 28 consecutive days. Liver tissue was fixed and the histopathological alterations were examined. The results showed that propoxur at high dose induced liver histopathological injury. Metabonomic analysis demonstrated that the levels of creatine and taurine markedly increased together with slight elevation of hippurate, glucose, and amino acids in low- and medium-dose groups. However, concentrations of urinary lactate, acetate, acetone, succinate, citrate, and 2-oxoglutarate increased in high-dose group. All these results suggested that propoxur could inhibit liver function through altering the energy and lipid metabolism. These data also supported the contention that the NMR-based metabonomic approach represents a promising new technology for the development of pesticide toxicity screening and mechanism exploration.
  International Journal of Toxicology 05/2012; 31(3):287-93. · 1.28 Impact Factor
• Article: Labdane-type diterpenoids from hairy root cultures of Coleus forskohlii, possible intermediates in the biosynthesis of forskolin.

  Yoshihisa Asada, Wei Li, Tomohiro Terada, Xinzhu Kuang, Qin Li, Takafumi Yoshikawa, Shogo Hamaguchi, Iyuki Namekata, Hikaru Tanaka, Kazuo Koike
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  ABSTRACT: Significant attention has been devoted to studying hairy root cultures as a promising strategy for production of various valuable secondary metabolites. These offer many advantages, such as high growth rate, genetic stability and being hormone-free. In this study, a detailed phytochemical investigation of the secondary metabolites of Coleus forskohlii hairy root cultures was undertaken and which resulted in the isolation of 22 compounds, including four forskolin derivatives and a monoterpene. Their structures were elucidated by extensive spectroscopic analyses. These compounds could be classified into four groups viz.: labdane-type diterpenes, monoterpenes, triterpenes and phenylpropanoid dimers. Apart from one compound, all labdane type diterpenes are oxygenated at C-11 as in forskolin and a scheme showing their biosynthetic relationships is proposed.
  Phytochemistry 04/2012; 79:141-6. · 3.35 Impact Factor
• Article: Learning, memory, and glial cell changes following recovery from chronic unpredictable stress.

  Yanqing Bian, Zhuo Pan, Ziyuan Hou, Cui Huang, Wei Li, Baohua Zhao
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  ABSTRACT: Previous research has indicated that chronic stress induces inflammatory responses, cognitive impairments, and changes in microglia and astrocytes. However, whether stress-induced changes following recovery are reversible is unclear. The present study examined the effects of chronic unpredictable stress (CUS) following recovery on spatial learning and memory impairments, changes in microglia and astrocytes, and interleukine-1β (IL-1β) and glial-derived neurotrophic factor (GDNF) levels. Mice were randomly divided into control, stress, and recovery groups, and CUS was applied to mice in the stress and recovery groups for 40 days. Following the application of CUS, the recovery group was allowed 40 days without stress. The results of the Morris water maze illustrated that CUS-induced spatial learning and memory impairments could be reversed or even improved by a period of recovery. Immunohistochemical tests revealed that CUS-induced alterations in microglia could dissipate with time in the CA3 region of the hippocampus and prelimbic areas. However, CUS-induced activation of astrocytes was sustained in the CA3 area following recovery. Western blot analyses revealed that CUS induced a significant increase of GDNF and a significant decrease in IL-1β. Additionally, increased GDNF levels were sustained in the hippocampus during recovery. In conclusion, this study provides evidence that CUS-induced learning and memory impairments could be reversible following recovery. However, activated astrocytes and increased GDNF levels in the hippocampus remained elevated after recovery, suggesting that activated astrocytes and increased GDNF play important roles in the adaptation of the brain to CUS and in repairing CUS-induced impairments during recovery.
  Brain research bulletin 04/2012; 88(5):471-6. · 2.18 Impact Factor
• Article: Ageing-associated changes in cellular immunity based on the SENIEUR protocol.

  J Wu, W Li, Z Liu, Y-Y Zhang, Y Peng, D-G Feng, L-H Li, L-N Wang, L Liu, L Li, J Liu
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  ABSTRACT: To investigate ageing-associated changes in cellular immunity, we recruited three groups of healthy subjects based on SENIEUR protocol criteria. In addition, 10 subjects were randomly selected from each group to isolate their T cells from peripheral blood mononuclear cells; T cell proliferation after phytohemagglutinin (PHA) stimulation was determined by methyl thiazolyl tetrazolium assays. There were no marked differences in the absolute numbers of peripheral blood T cells, NK cells or B cells among the three groups (P > 0.05). Also, no significant differences were noted in the numbers of CD4+ cells, CD8+ cells, or the CD4+/CD8+ ratios (P > 0.05). After PHA stimulation, T cell proliferation was markedly increased, with the highest level in group C and the lowest level in group A (P < 0.05). Cytokine-induced killer tumouricidal activities were also dramatically increased, with the highest activity in group C and the lowest activity in group A (P < 0.05). Our findings suggest that the number of immune cells remains unchanged with advanced age. However, there is a trend for decreased cellular immunity with an increase in age.
  Scandinavian Journal of Immunology 03/2012; 75(6):641-6. · 2.23 Impact Factor
• Article: Stereoselective dissipation of epoxiconazole in grape (Vitis vinifera cv. Kyoho) and soil under field conditions.

  Hongwu Liang, Jing Qiu, Li Li, Wei Li, Zhiqiang Zhou, Fengmao Liu, Lihong Qiu
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  ABSTRACT: Stereoselective dissipation of epoxiconazole had been studied in grape and soil during plant growing under field conditions in this paper. A sensitive and rapid chiral method was developed and validated for the determination of epoxiconazole stereoisomers in grape and soil based on liquid chromatography coupled with triple quadrupole mass spectrometry (LC-MS/MS). Phenomenex Lux Cellulose-1 column was used for enantioseparation with a mixture of acetonitrile/water (90/10, v/v) as mobile phase at flow rate of 0.3 mL min(-1). Fortified recoveries in grape and soil samples ranged from 76.0% to 91.9% and relative standard deviations were less than 11.4% with fortified levels of 0.025-1.0 mg kg(-1). The limits of detection and quantification were 0.005 mg kg(-1) and 0.025 mg kg(-1), respectively, with linear calibration curves extending up to 5.0 mg kg(-1). The field experimental results showed that dissipations of epoxiconazole stereoisomers in grape followed first-order kinetics (R(2)>0.92) and stereoselectivity occurred in 2 h after spraying. The (-)-stereoisomer with half-life of 9.3 d degraded faster than (+)-stereoisomer with that of 13.2 d, and resulted in relative enrichment of (+)-stereoisomer. However, the stereoisomeric dissipations in soil were triphasic ("increase-decrease-steady") with lower dissipation rates, and also occurred with preferential degradation of (-)-stereoisomer under field condition. The results for stereoselective dissipations can be applied for food and environmental assessments of chiral pesticides.
  Chemosphere 03/2012; 87(8):982-7. · 3.21 Impact Factor
• Article: An NMR-based metabonomic investigation of the subacute effects of melamine in rats.

  Ying-Jian Sun, Hui-Ping Wang, Yu-Jie Liang, Lin Yang, Wei Li, Yi-Jun Wu
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  ABSTRACT: The subacute toxic effects of 28 days of exposure to three dosages (250, 500, 1000 mg/kg/day) of melamine on Wistar rats were investigated using nuclear magnetic resonance spectra, histopathological examination, and biochemical analysis. Rats treated with melamine developed adverse health effects compared to the controls, including decrease in body weight and kidney damage. Blood biochemical analysis showed that the blood urea nitrogen and creatinine increased distinctly compared to the control group. Urinary metabonomic analysis indicated that melamine caused an increase in succinate and citrate. Serum metabonomic analysis showed that the lowest dose led to an increase in dimethylglycine, N-acetylglycoprotein (NAC), accompanied by a decrease in taurine and glucose. Rats treated with the highest dose developed high levels of serum choline and 3-hydroxybutyrate (3-HB) together with low lactate levels. Metabonomic analysis of liver tissue indicated that melamine caused an increase in NAC, choline, and creatine, accompanied by a decrease in lactate, trimethylamine-N-oxide, glutamate, and glucose. All three dosages resulted in an increase in glutamate, lactate, choline, glucose, and animo acids and a decrease in 3-HB and pyruvate in aqueous kidney extract. These results indicate that melamine not only caused renal disfunction but also disturbed the liver's glucose, protein, and nitrogen metabolism.
  Journal of Proteome Research 03/2012; 11(4):2544-50. · 5.11 Impact Factor
• Article: Stereoselective separation and determination of triadimefon and triadimenol in wheat, straw, and soil by liquid chromatography-tandem mass spectrometry.

  Hongwu Liang, Jing Qiu, Li Li, Wei Li, Zhiqiang Zhou, Fengmao Liu, Lihong Qiu
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  ABSTRACT: A sensitive and rapid analytical method was developed for simultaneous determination of triadimefon (TF) and triadimenol (TN) stereoisomers in wheat, straw, and soil by liquid chromatography coupled with triple quadrupole mass spectrometry (LC-MS/MS). The direct enantioseparation of TF and TN was performed on a Lux cellulose-1 column packed with cellulose-tris-(3,5-dimethylphenylcarbamate). The effects of mobile-phase composition on the separation were investigated and stereoisomeric elution orders were confirmed with a polarimeter detector. The pesticides were extracted from samples with acetonitrile and cleaned up by solid-phase extraction or activated carbon. Based on the developed stereoselective LC-MS/MS method, for TF and TN stereoisomers, good linearities were obtained over the concentration range of 0.003-4 mg/L; recoveries were 84.2-102.7% in wheat, 84.0-104.0% in straw, and 85.2-106.8% in soil at spiked concentrations of 0.007-2.0 mg/kg; intra-day and inter-day assay precisions were below 12.2%. Limits of detection (LODs) and limits of quantification (LOQs) in wheat, straw, and soil were 0.001-0.005 mg/kg and 0.007-0.02 mg/kg, respectively. Finally, the method was successfully applied to detect TF and TN stereoisomers in wheat, straw, and soil samples from residual trials in farm.
  Journal of Separation Science 11/2011; 35(1):166-73. · 2.73 Impact Factor
• Article: The dissipation of ethofenprox in cabbage and soil under open conditions.

  Dali Sun, Li Li, Hongwu Liang, Wei Li, Ran Ji, Yijun Wu, Chenglan Liu
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  ABSTRACT: The dissipation of ethofenprox in cabbage and soil under open conditions was investigated at two primary cabbage-growing regions, Beijing and Kunming in China. Samples were extracted with acetonitrile and determined by ultra-performance liquid chromatography with a single quadrupole detector. Dissipation of ethofenprox from cabbage and soil can be best explained by a first-order decay process. The half-lives of ethofenprox were 1.9 and 2.3 days in cabbage and 20.0 and 13.0 days in soil at Beijing and Kunming, respectively. The concentration of ethofenprox residue was reduced by 90% taking 7 and 60 days in cabbage and soil. Dissipation rates in cabbage and soil at two geographically separated experimental fields differed, suggesting that this was affected by complicated factors, such as local climate and soil characteristics. These data could provide guidance for the proper and safe use of this pesticide on cabbage in China.
  Environmental Monitoring and Assessment 10/2011; 184(9):5743-7. · 1.40 Impact Factor
• Article: Determination of hymexazol in cucumber and soil samples by derivatization using GC-FPD.

  Dali Sun, Li Li, Ran Ji, Wei Li, Huochun Ye, Yijun Wu, Chenglan Liu
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  ABSTRACT: A sensitive and effective analytical method for the determination of hymexazol in cucumber and soil samples by gas chromatography with a flame photometric detector was developed. This method was validated with fortified at three different levels of 0.2, 1.0 and 5.0 mg/kg. Average recoveries obtained from cucumber and soil samples at three fortified levels were 94.0%-107.8% with relative standard deviations (RSDs) of less than 11.4%. Limits of quantification (LOQ) in cucumber and soil were 0.2 mg/kg. The method was successfully applied to determine hymexazol in real samples of cucumber and soil under open fields.
  Bulletin of Environmental Contamination and Toxicology 09/2011; 87(6):653-6. · 1.02 Impact Factor
• Article: The decline and residues of hexaconazole in tomato and soil.

  Hongwu Liang, Li Li, Wei Li, Yijun Wu, Fengmao Liu
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  ABSTRACT: The decline and terminal residues of hexaconazole in tomato and soil in open field were studied. Hexaconazole residues were determined by gas chromatography coupled with an electron capture detector. Recoveries were between 89% and 110% with RSD of 2.99-5.88% in tomato and 90-119% with RSD of 1.15-5.76% in soil at spiked levels of 0.01, 0.1, and 1 mg/kg, respectively. The limit of detection of hexaconazole was 6.3 × 10(-12) g. The decline rates of hexaconazole were described using first-order kinetics and the mean half-lives of hexaconazole in tomato and soil were 4.3 and 18.1 days, respectively. The terminal residues in tomato at interval of 7 days at the dosage of 150 g.a.i./hm(2) for three or four times were all below 0.1 mg/kg. This work would be the guidance of establishing the maximum residue limit of hexaconazole in tomato in China.
  Environmental Monitoring and Assessment 04/2011; 184(3):1573-9. · 1.40 Impact Factor
• Article: Dissipation and residue of dimethomorph in pepper and soil under field conditions.

  Hongwu Liang, Li Li, Wei Li, Yijun Wu, Zhiqiang Zhou, Fengmao Liu
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  ABSTRACT: The dissipation and residual levels of dimethomorph in pepper and soil under field conditions were determined by gas chromatography with an electron capture detector (GC-ECD). The dissipation rates of dimethomorph were described using first-order kinetics and its half-life ranged from 1.7 to 3.8 days in pepper and 11.5-18.5 days in soil. At harvest time, the terminal residues of dimethomorph were below the EU's maximum residue limit (MRL, 0.5 mg kg⁻¹) in pepper when measured 7 days after the final application, which suggested that the use of this fungicide was safe for humans. The collected field samples were stable for up to two months when refrigerated at -20°C. The residues persistence varied among three geographically separated experimental fields, suggesting that it might be affected by climatic, soil properties and local microorganisms. These results will be helpful in setting MRL guidance for dimethomorph in pepper in China.
  Ecotoxicology and Environmental Safety 03/2011; 74(5):1331-5. · 2.29 Impact Factor
• Article: The dissipation rates of trichlorfon and its degradation product dichlorvos in cabbage and soil.

  Wei Li, Yan Ma, Li Li, Dong-Mei Qin, Yi-Jun Wu
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  ABSTRACT: The residual levels and dissipation rate of trichlorfon, and its degradation product, dichlorvos, in cabbage crops and the soil in which these were grown, were determined by gas chromatography at two geographically distant experimental sites, one in Kunming and one in Beijing, China. Trichlorfon was applied at two dosages (900 g ai ha(-1) and 1350 g ai ha(-1)). Maximum final residues of trichlorfon in soil and cabbage were 1.23 mg kg(-1) and 1.81 mg kg(-1) respectively at Kunming, and 0.35 mg kg(-1) and 0.70 mg kg(-1) respectively at Beijing. However, the final residues of dichlorvos in both cabbage and soil was only 0.04 mg kg(-1) at Kunming, and only 0.03 mg kg(-1), or "not detectable", at Beijing. The mean half-life of trichlorfon in cabbage was 1.80 d with a dissipation rate of 90% over 5 d, while that in soil was 3.05 d with a dissipation rate of 90% over 14 d at one experimental site. The dissipation rates of trichlorfon and its degradation product dichlorvos at the two experimental sites were different, suggesting that degradation of these pesticides was affected by local soil characteristics and climate. When applied at both the recommended dosage and at 1.5 times this, no detectable residues of either trichlorfon or dichlorvos were found in soil or cabbage at harvest. Although trichlorfon can easily degrade into dichlorvos, which is highly toxic to humans and other animals, the observed low residual levels of dichlorvos suggest that trichlorfon is safe when applied at the recommended dosage.
  Chemosphere 02/2011; 82(6):829-33. · 3.21 Impact Factor
• Article: The environmental fate of different forms of ZJ0702 in open rape field and MRL calculation.

  Li Li, Hongwu Liang, Wei Li, Ran Ji
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  ABSTRACT: In the present work, the environmental fate, including residual level and dissipation rate of two formulations of ZJ0702 (a new pyrimidine salicylic herbicide which showed good inhibitory effect on the weeds in rape fields), EC and SC, were determined by high performance liquid chromatography with DAD. The herbicide was used in Hangzhou and Kunming in rape fields at the same time for 2 years. The results were that half-lives of ZJ0702 in rape ranged from 1.2-6.8 days, while in soil samples were from 15.2-47.1 days. On the sampling days, the final residues of ZJ0702 in rapeseed were below the limit of quantitation (0.02 mg/kg). The differences of dissipation rate suggest that local soil characteristics and climate, and the formulations would affect the decline of ZJ0702. The low final residue levels of ZJ0702 in rapeseed and soil indicated that this new pesticide was environmentally safe. It was recommended that MRL for ZJ0702 in rapeseed be 1 mg/kg in China.
  Toxicology mechanisms and methods 11/2010; 21(1):37-40. · 1.03 Impact Factor
• Article: Regulation of neuropathy target esterase by the cAMP/protein kinase A signal.

  Jia-Xiang Chen, Ding-Xin Long, Wei-Yuan Hou, Wei Li, Yi-Jun Wu
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  ABSTRACT: As a phospholipase B, neuropathy target esterase (NTE) is responsible for the conversion of phosphatidylcholine (PC) to glycerophosphocholine (GPC). We examined the role of cAMP in the regulation of NTE in mammalian cells. Endogenous NTE activity was increased by cAMP-elevating chemicals, including dibutyryl cAMP, forskolin and forskolin plus 1-isobutyl-3-methylxanthine (IBMX), but decreased by the adenyl cyclase inhibitor SQ22536 which can reduce intracellular cAMP levels. Exogenous GFP-tagged NTE activity was not affected by changes in intracellular cAMP. NTE protein levels were up-regulated by the cAMP-elevating reagents and down-regulated by the inhibitor. The effect of the adenyl cyclase activator forskolin on NTE protein and mRNA levels was blocked by pretreatment with the protein kinase A (PKA) activity inhibitor H89. In addition, we found that changes in GPC, but not PC, levels were correlated with cAMP induced changes in NTE activity. These results are the first evidence that cAMP/PKA signals regulate NTE expression and GPC content in mammalian cells.
  Pharmacological Research 04/2010; 62(3):259-64. · 4.44 Impact Factor
• Article: Effects of avermectins on neurite outgrowth in differentiating mouse neuroblastoma N2a cells.

  Ying-Jian Sun, Ding-Xin Long, Wei Li, Wei-Yuan Hou, Yi-Jun Wu, Jian-Zhong Shen
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  ABSTRACT: Avermectins (AVMs) are macrocyclic lactone compounds that have been widely used as parasiticides in veterinary and human medicine and as pesticides in agriculture and horticulture. The multidrug resistance transporter, P-glycoprotein (P-gp), is associated with the efflux transport of AVMs and other drugs across the blood-brain and placental barrier, and plays an important role in attenuating the neurotoxicity and developmental toxicity of AVMs. In this study, the mouse neuroblastoma N2a cell line was used to investigate the neurotoxicity of two AVM derivatives: abamectin (ABM) and doramectin (DOR). We found that both these compounds caused significant dose-dependent inhibition of neurite growth in differentiating N2a cells. In addition, Western blotting analysis showed that ABM and DOR significantly inhibited the expression of not only P-gp but also the cytoskeletal proteins, beta-actin and beta-tubulin. This suggests ABM and DOR may inhibit neurite growth by down-regulating the expression of P-gp and cytoskeletal proteins. Furthermore, knockdown of P-gp expression by RNA interference in N2a cells reduced neurite growth even in the absence of ABM and DOR, and reduced it even more in the presence of low levels of these compounds. These results suggest that even subcytotoxic levels of ABM and DOR can be neurotoxic in differentiating cells and that this neurotoxicity may, at least in part, be the result of the down-regulation of P-gp and cytoskeletal proteins.
  Toxicology Letters 10/2009; 192(2):206-11. · 3.23 Impact Factor
• Article: Effects of methamidophos and deltamethrin on in vitro protein phosphorylation in Monochamus alternatus

  Jie Liu, Xi-Wu Gao, Yi-Jun Wu, Wei Li, Qi-Lian Qin, Jiang-Hua Sun
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  ABSTRACT: Monochamus alternatus Hope (Coleoptera: Cerambycidae) is not only a serious pest insect to pine trees but also the main vector of pine wood nemadote Bursaphelenchus xylophilus, which causes pine wilt disease. To explore the insecticidal mechanism of insecticides to M. alternatus, we chose methamidophos and deltamethrin as the representatives of two groups of insecticides (organophosphates and pyrethroids), which are widely used for pest control in China and investigated their effects on phosphorylation of proteins from the insect. Phosphorylation of proteins from the insect fat body and head was determined by in vitro32P-labelling. In the fat body, deltamethrin obviously reduced basal phosphorylation levels of proteins at 111, 95, 77, and 44 kDa, but enhanced the basal phosphorylation level of a protein at 138 kDa. However, in the presence of calmodulin but not cyclic adenosine monophosphate (cAMP), deltamethrin increased phosphorylation of the protein at 111 kDa. In the head, deltamethrin inhibited basal phosphorylation levels of proteins at 113, 98, and 51 kDa, but potentiated phosphorylation of a protein at 167 kDa activated by cAMP. Methamidophos inhibited phosphorylation of a protein at 44 kDa in the fat body. Although methamidophos did not impact basal phosphorylation levels of any proteins in the head, it inhibited calcium/calmodulin (Ca2+/CaM)-stimulated phosphorylation of a protein at 51 kDa. Together, our data indicate that methamidophos and deltamethrin altered phosphorylation levels of various proteins in the head and fat body of the pine insect and these two kinds of insecticides acted on the proteins that can be phosphorylated in the tissues respectively, which is possibly related to their toxicity.
  Insect Science 11/2008; 15(6):529 - 535. · 1.10 Impact Factor
• Article: Use of graphitic carbon black and primary secondary amine for determination of 17 organophosphorus pesticide residues in spinach.

  Li Li, Wei Li, Jing Ge, Yijun Wu, Shuren Jiang, Fengmao Liu
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  ABSTRACT: Graphitized carbon black (GCB) and primary secondary amine (PSA) as dispersive-SPE sorbents were applied to optimize the method for the determination of 17 organophosphorus pesticides in spinach which contained so many pigments using GC with flame photometric detector (FPD). The sample was extracted with ACN, and an aliquot of the extract was concentrated to near dryness. Ethyl acetate or acetone was chosen as the dissolving solvent. Subsequently, dispersive-SPE was used for cleanup, and the type and quantity of sorbents (GCB, PSA and activated carbon) were tested in the experiments. The best results were when acetone was used to dissolve and 30 mg each of GCB and PSA for cleanup. In this condition, recoveries of pesticides analyzed were between 52-117% with RSD below 10%, and LOQ ranged from 10 to 20 microg/kg. This method was simple, effective and efficient, and can protect the GC system to some extent.
  Journal of Separation Science 11/2008; 31(20):3588-94. · 2.73 Impact Factor
• Article: Triazophos residues and dissipation rates in wheat crops and soil.

  Wei Li, Shao-Ping Qiu, Yi-Jun Wu
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  ABSTRACT: The residual level and dissipation rate of triazophos in wheat crops and the soil in which they were grown were determined by gas chromatography (GC). Maximum final residues of triazophos in wheat grain, stems and leaves, and soil were 1.865, 44.506, and 0.973 mg/kg, respectively. The mean half-life of triazophos in wheat plants (grain, stems, and leaves) was 5.22 days with a dissipation rate of 90% over 14 days. The half-life in soil was 7.93 days with a dissipation rate of 90% over 21 days. Dissipation rates in two geographically separated experimental fields differed, suggesting that this was affected by local soil characteristics and climate. Although residual levels of triazophos in wheat plants may pose risks to the health of humans and other animals, comparatively low residues in soil suggest that this pesticide may be otherwise environmentally safe.
  Ecotoxicology and Environmental Safety 03/2008; 69(2):312-6. · 2.29 Impact Factor
• Article: A Method for Quantifying Azoxystrobin Residues in Grapes and Soil Using GC with Electron Capture Detection

  Wei Li, Yi-Jun Wu, Dong-Mei Qin, Yan Ma, Ying-Jian Sun, Shao-Ping Qiu
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  ABSTRACT: A relatively simple method for the determination of azoxystrobin residues in grapes and soil using gas chromatography equipped with electron capture detector (GC-ECD) is described. Samples were extracted with acetone, and further partitioned with dichloromethane and petroleum ether. The extracts were then cleaned up in a glass clean-up column filled with active charcoal and silica gel, and eluted with dichloromethane/ethyl acetate (70:30, v/v). The eluate was collected and concentrated for GC-ECD analysis. The results showed good linearity (r 2=0.9998) over the concentration range of 6.25–400ngmL−1. The limits of detection (LOD) and quantification (LOQ) of azoxystrobin were 3 and 10ngmL−1. Recovery from soil and grape samples was in the range of 83.52–107.36 and 82.21–107.31%, with corresponding relative standard deviations (RSD) of 5.21–9.11 and 4.53–5.90% for the three fortified levels. Inter- and intra-day RSDs were in the range of 0.87–6.76 and 2.01–5.46%. The accuracy and sensitivity of the GC-ECD method was independently confirmed by LC and GC-MS. It was demonstrated that the proposed method was simple and efficient, and particularly suitable for detecting azoxystrobin residues in grapes and soil.
  Chromatographia 01/2008; 67(9):761-766. · 1.20 Impact Factor