To ensure the safety of the commercially available chenpi,a convenient and fast analytical method was developed for the determination of 133 pesticide residues in chenpi using gas chromatography-tandem mass spectromet...To ensure the safety of the commercially available chenpi,a convenient and fast analytical method was developed for the determination of 133 pesticide residues in chenpi using gas chromatography-tandem mass spectrometry(GC-MS/MS).In this study,different extraction solvents,redissolution solvents and adsorbents were tested according to the recovery and purification effect to obtain a modified QuEChERS method.The samples were extracted with acetonitrile.During the clean-up step,octadecyl-modified silica(C18)and graphitized carbon black(GCB)were selected,and aminopropyl(NH2)was used instead of primary secondary amine(PSA)because of its weaker ion exchange capacity which had little effect on the recovery of ditalimfos.Samples were quantified by matrix-matched calibration with internal standards.All pesticides showed good linearity in the respective range,both with values of r2>0.99.The average recoveries of the pesticides spiked samples ranged from 70.0% to 112.2% with the RSDs of 0.2%–14.4%.The modified QuEChERS method was validated and applied to twenty real samples.Five pesticides were found in eight batches,but no pesticide exceeded the maximum residue limits(MRL,MRL reference to European commission).展开更多
With the development of portable communication devices and electric vehicles, there is a great need for energy storage devices with lighter weight and higher energy density. In this paper, a new method by combining wa...With the development of portable communication devices and electric vehicles, there is a great need for energy storage devices with lighter weight and higher energy density. In this paper, a new method by combining waster-paper-synthesized conductive paper(CP) and active material Mn O2 together is developed to obtain a new type of anode without any binder for lithium ion batteries. By this way, we can obtain low density anode with active material in CP, instead of the commonly-used heavy metal current collector. Also, binder has been abandoned, which are usually used to combine active material into anode, to further decrease weight. The multi walled carbon nanotube(MWCNT) was added in serves as a component of CP and the conductive agent for active material. Compared to traditional anode coated on Cu current collector, the CP-combined anode can greatly improve the electrochemical performance of active material Mn O2. It can let more particles to fully participate in the reaction and therefore boost the specific capacity to a great extent(about 3 times higher). It delivered an initial specific capacity of 1629.9 m A h g^-1 at a current density of 100 m A g^-1 and maintained about 67% even after 100 cycles.What’s more, it shows reversible capacity of about 260 m A h g^-1 at high current density of 1000 m A h g^-1.Our original synthesis method of anode, which shows far-reaching referential value and environmental significance, can be generalized to other electrodes and other battery systems.展开更多
文摘To ensure the safety of the commercially available chenpi,a convenient and fast analytical method was developed for the determination of 133 pesticide residues in chenpi using gas chromatography-tandem mass spectrometry(GC-MS/MS).In this study,different extraction solvents,redissolution solvents and adsorbents were tested according to the recovery and purification effect to obtain a modified QuEChERS method.The samples were extracted with acetonitrile.During the clean-up step,octadecyl-modified silica(C18)and graphitized carbon black(GCB)were selected,and aminopropyl(NH2)was used instead of primary secondary amine(PSA)because of its weaker ion exchange capacity which had little effect on the recovery of ditalimfos.Samples were quantified by matrix-matched calibration with internal standards.All pesticides showed good linearity in the respective range,both with values of r2>0.99.The average recoveries of the pesticides spiked samples ranged from 70.0% to 112.2% with the RSDs of 0.2%–14.4%.The modified QuEChERS method was validated and applied to twenty real samples.Five pesticides were found in eight batches,but no pesticide exceeded the maximum residue limits(MRL,MRL reference to European commission).
基金financial support from Petro China Innovation Foundation (2017D-50070607)China Scholarship Council (201607890002)
文摘With the development of portable communication devices and electric vehicles, there is a great need for energy storage devices with lighter weight and higher energy density. In this paper, a new method by combining waster-paper-synthesized conductive paper(CP) and active material Mn O2 together is developed to obtain a new type of anode without any binder for lithium ion batteries. By this way, we can obtain low density anode with active material in CP, instead of the commonly-used heavy metal current collector. Also, binder has been abandoned, which are usually used to combine active material into anode, to further decrease weight. The multi walled carbon nanotube(MWCNT) was added in serves as a component of CP and the conductive agent for active material. Compared to traditional anode coated on Cu current collector, the CP-combined anode can greatly improve the electrochemical performance of active material Mn O2. It can let more particles to fully participate in the reaction and therefore boost the specific capacity to a great extent(about 3 times higher). It delivered an initial specific capacity of 1629.9 m A h g^-1 at a current density of 100 m A g^-1 and maintained about 67% even after 100 cycles.What’s more, it shows reversible capacity of about 260 m A h g^-1 at high current density of 1000 m A h g^-1.Our original synthesis method of anode, which shows far-reaching referential value and environmental significance, can be generalized to other electrodes and other battery systems.
