An efficient method using multiwalled carbon nanotubes(MWCNTs)as dispersive solid-phase extraction sorbent was established for determining chlorantraniliprole residues in fresh tea leaves,which are known to be a troub...An efficient method using multiwalled carbon nanotubes(MWCNTs)as dispersive solid-phase extraction sorbent was established for determining chlorantraniliprole residues in fresh tea leaves,which are known to be a troublesome matrix containing abundant pigments,via gas chromatography with an electron capture detector.Acetonitrile was used as the extraction solvent,with sodium chloride enhancing the analyte partition in the organic phase.The optimal mixture of MWCNTs and primary secondary amine(PSA)was based on the distribution of the target analyte recovery and on the clean-up efficiency;while matrix-matched calibration was recommended to combat the matrix effect.Mean recoveries of 95.2%–108.8%were obtained with intraday and interday precisions of less than 7.9%and 10.3%,respectively.Good linearity was observed for concentrations of 0.02–1.0 mg/kg with a correlation coefficient of 0.9984.The limits of detection and quantification were 0.005 mg/kg and 0.02 mg/kg,respectively.The method was employed to investigate the dissipation dynamics of chlorantraniliprole in fresh tea leaves with real field samples.Consequently,the dissipation rates of chlorantraniliprole in fresh tea leaves followed pseudo-first-order kinetics with a half-life of 1.9 d,and the average chlorantraniliprole residue content was below 0.02 mg/kg with a harvest withholding period of 14 d.展开更多
Numerous isolated shallow seabed domes with depressions were discovered in the North Yellow Sea in a high-resolution multibeam echosounder survey. Twelve domes were located within a 11 km by 17 km survey area. The dom...Numerous isolated shallow seabed domes with depressions were discovered in the North Yellow Sea in a high-resolution multibeam echosounder survey. Twelve domes were located within a 11 km by 17 km survey area. The domes in this area were between 0.1 m and 1.0 m high with diameters ranging from 250 to 1 700 m. They were surrounded by corresponding depressions and displayed characteristic shapes ranging from circular to elliptical. The acoustic anomalies displayed on the high resolution sub-bottom profile images demonstrated that shallow gas accumulated just beneath these domes, suggesting that the migration and accumulation of the shallow gas caused the formation of these features. Accumulation atop the seabed domes and erosion within the depressions, as indicated by the lithological features of the sediment cores, suggested that seabed bottom currents also played a role in the formation and evolution of these features. In addition, the simultaneous decrease in the chlorite and sulfate content in core d pore water samples confirmed the presence of submarine fresh/brackish groundwater, which is of interest for hydrological budgets and may be a significant component of the regional hydrologic balance. Our findings suggested that shallow gas accumulation and migration are likely coupled to localized groundwater discharge at this domed site.展开更多
Objective] This study aimed to detect al organophosphate, organochlorine and pyrethroid pesticide residues in fresh sweet corn in one determination using a gas chromatograph. [Method] The pesticide residues in fresh s...Objective] This study aimed to detect al organophosphate, organochlorine and pyrethroid pesticide residues in fresh sweet corn in one determination using a gas chromatograph. [Method] The pesticide residues in fresh sweet corn were ex-tracted and loaded to simultaneously the gas chromatograph Agilent 6890N which was equipped with two autosamplers, two columns and two detectors. [Result] Al the 26 pesticides were completely separated and eluted out within 25 min. The re-coveries of standard addition of the 26 pesticides ranged from 76% to 106%, with relative standard deviations （RSD） ranging from 0.5% to 8.9%. The linear regression equation fit wel from 0.050 to 1.500 mg/L corn extract （r2＆gt;0.996）. [Conclusion] The method is accuracy, which meets the requirements of pesticide residue analysis and can be used for the rapid detection, qualitative and quantitative analysis of pesticide residues in fresh sweet corn.展开更多
基金Science and Technology Project of Suzhou(Grant Nos.:SNG201622 and SNG201644)。
文摘An efficient method using multiwalled carbon nanotubes(MWCNTs)as dispersive solid-phase extraction sorbent was established for determining chlorantraniliprole residues in fresh tea leaves,which are known to be a troublesome matrix containing abundant pigments,via gas chromatography with an electron capture detector.Acetonitrile was used as the extraction solvent,with sodium chloride enhancing the analyte partition in the organic phase.The optimal mixture of MWCNTs and primary secondary amine(PSA)was based on the distribution of the target analyte recovery and on the clean-up efficiency;while matrix-matched calibration was recommended to combat the matrix effect.Mean recoveries of 95.2%–108.8%were obtained with intraday and interday precisions of less than 7.9%and 10.3%,respectively.Good linearity was observed for concentrations of 0.02–1.0 mg/kg with a correlation coefficient of 0.9984.The limits of detection and quantification were 0.005 mg/kg and 0.02 mg/kg,respectively.The method was employed to investigate the dissipation dynamics of chlorantraniliprole in fresh tea leaves with real field samples.Consequently,the dissipation rates of chlorantraniliprole in fresh tea leaves followed pseudo-first-order kinetics with a half-life of 1.9 d,and the average chlorantraniliprole residue content was below 0.02 mg/kg with a harvest withholding period of 14 d.
基金Supported by the Strategic Priority Research Program,CAS(No.XDA19060402)the NSFC-Shandong Joint Fund for Marine Science Research Centers(No.U1606401)+1 种基金the International Partnership for Innovative Team Program(No.20140491526)the Chinese Academy of Sciences,and the Taishan Scholar Project Funding(No.tspd20161007)
文摘Numerous isolated shallow seabed domes with depressions were discovered in the North Yellow Sea in a high-resolution multibeam echosounder survey. Twelve domes were located within a 11 km by 17 km survey area. The domes in this area were between 0.1 m and 1.0 m high with diameters ranging from 250 to 1 700 m. They were surrounded by corresponding depressions and displayed characteristic shapes ranging from circular to elliptical. The acoustic anomalies displayed on the high resolution sub-bottom profile images demonstrated that shallow gas accumulated just beneath these domes, suggesting that the migration and accumulation of the shallow gas caused the formation of these features. Accumulation atop the seabed domes and erosion within the depressions, as indicated by the lithological features of the sediment cores, suggested that seabed bottom currents also played a role in the formation and evolution of these features. In addition, the simultaneous decrease in the chlorite and sulfate content in core d pore water samples confirmed the presence of submarine fresh/brackish groundwater, which is of interest for hydrological budgets and may be a significant component of the regional hydrologic balance. Our findings suggested that shallow gas accumulation and migration are likely coupled to localized groundwater discharge at this domed site.
基金Supported by Science and Technology Research Program of Huizhou City~~
文摘Objective] This study aimed to detect al organophosphate, organochlorine and pyrethroid pesticide residues in fresh sweet corn in one determination using a gas chromatograph. [Method] The pesticide residues in fresh sweet corn were ex-tracted and loaded to simultaneously the gas chromatograph Agilent 6890N which was equipped with two autosamplers, two columns and two detectors. [Result] Al the 26 pesticides were completely separated and eluted out within 25 min. The re-coveries of standard addition of the 26 pesticides ranged from 76% to 106%, with relative standard deviations （RSD） ranging from 0.5% to 8.9%. The linear regression equation fit wel from 0.050 to 1.500 mg/L corn extract （r2＆gt;0.996）. [Conclusion] The method is accuracy, which meets the requirements of pesticide residue analysis and can be used for the rapid detection, qualitative and quantitative analysis of pesticide residues in fresh sweet corn.
