Atrazine accumulation,oxidative stress,and defense response in maize seedlings exposed to extraneous atrazine were studied.Accumulation of atrazine in maize increased with increasing exposure concentration.The abscisic acid（ABA） content was positively correlated with the atrazine concentrations in maize roots and shoots（p 0.05）.Hydroxyl radical（.OH） in maize was determined in vivo with electron paramagnetic resonance spectroscopy.Its intensity was positively correlated with atrazine concentration in roots and shoots（p 0.05）,and higher level of.OH generated in roots than in shoots corresponded to the major accumulation of atrazine in roots.Superoxide dismutase,peroxidase and catalase in roots were up-regulated by atrazine exposure at 1 mg/L compared to the control and malondialdehyde content in roots was enhanced when atrazine exposure concentration reached 10 mg/L.These results suggested the exposure and accumulation of atrazine caused oxidative toxicity and antioxidant response in maize.
The electrocatalytic dechlorination of 4-chlorophenol(4-CP) in aqueous solution was studied by using a palladium-nickel bimetallic composite catalyst deposited on nickel foam(Pd-Ni/Ni foam) as the cathode.The Pd-Ni composite particles with a diameter of less than 50 nm were finely dispersed on the Ni foam surface.The Pd-Ni/Ni foam electrode exhibited higher dechlorination efficiency than single Pd or Ni supported on Ni foam electrodes.High-performance liquid chromatography analysis verified that phenol was the main dechlorination product.For an applied current of 20 mA,a bulk solution temperature of 15℃,and an initial 4-CP concentration of 1 mmol·L-1,dechlorination efficiency of 82% was observed.Based on electrochemical impedance spectroscopic results and the current efficiency of 4-CP dechlorination at different applied currents on various electrodes,the authors determined the rate-limiting step under various polarization conditions in the experiments.
A method was developed for the analysis of hydroxylated brominated diphenyl ethers (OH-PBDEs) in plant samples using an ultra performance liquid chromatography-triple quadrupole mass spectrometer (UPLC-ESI-MS/MS) in negative mode. Plant samples were extracted and cleaned up through florisil column, resolved on a 100 mm C18 column with linear gradient elution and detected by mass spectrometry in multiple reaction monitoring (MRM) mode. The method provided good recoveries rang- ing from 68.2% to 94.6%, relative standard deviation (RSD) in the range of 3.2% - 9.1%, and limits of quantification (LOQ) defined as the signal-to-noise ratio of 10 of 0.3-2.1 ng/g. It allowed a fast separation and sensitive quantification of the isomers and homologues of seven OH-PBDE congeners 2′-OH-BDE-3, 3′-OH-BDE-7, 4′-OH-BDE-17, 3′-OH-BDE-28, 3-OH-BDE-47, 5-OH-BDE-47 and 6-OH-BDE-47. The method was successfully applied to identify and quantify the formation of hydroxylat- ed metabolites in alfalfa exposed to BDE-209. Five OH-PBDEs were detected in plant tissues, and more congeners were found in roots than in shoots. To our knowledge, this work represents the first attempt to validate UPLC-MS/MS method to quantify OH-PBDEs in plant samples without derivatization.
WANG SenWU TongHUANG HongLinPING HuaLU AnXiangZHANG ShuZhen
