目的:建立高效液相色谱-串联质谱法测定蜂王浆中草甘膦、氨甲基膦酸和N-乙酰草甘膦含量的分析方法。方法:样品经0.2mol/L碳酸氢铵水溶液提取,采用Waters PRIME HLB固相萃取小柱净化,以Dikma Polyamino HILIC色谱柱进行色谱分离,多反应监...目的:建立高效液相色谱-串联质谱法测定蜂王浆中草甘膦、氨甲基膦酸和N-乙酰草甘膦含量的分析方法。方法:样品经0.2mol/L碳酸氢铵水溶液提取,采用Waters PRIME HLB固相萃取小柱净化,以Dikma Polyamino HILIC色谱柱进行色谱分离,多反应监测(MRM)监测模式测定,外标法定量。结果:3种化合物在20~400μg/L的浓度范围内线性关系良好,检出限为20μg/kg,定量限位50μg/kg。空白蜂王浆样品的3水平加标回收率为74.0%~96.1%,相对标准偏差为5.1%~9.6%。结论:该方法适用于蜂王浆中草甘膦及其两种代谢物残留的检测。展开更多
采用溶胶-凝胶自燃烧法合成镧掺杂六角钡铁氧体（LaxBa1-xFe12O19）纳米粉体,细致研究了镧掺杂量对所合成六角钡铁氧体纳米粉体物相形成、颗粒尺寸以及电磁特性等的影响。结果表明：随着镧掺杂量的提高,获得纯相掺杂铁氧体粉体的热处理...采用溶胶-凝胶自燃烧法合成镧掺杂六角钡铁氧体（LaxBa1-xFe12O19）纳米粉体,细致研究了镧掺杂量对所合成六角钡铁氧体纳米粉体物相形成、颗粒尺寸以及电磁特性等的影响。结果表明：随着镧掺杂量的提高,获得纯相掺杂铁氧体粉体的热处理温度提高,当热处理温度为1000℃时,所得纯相镧掺杂六角铁氧体粉体Ba位La掺杂量x（摩尔分数）可达0.20;镧元素掺杂抑制了后续热处理过程中晶粒长大,对于所合成产物的颗粒呈现出一定细化作用,这在较高热处理温度下更为明显;镧掺杂改性六角钡铁氧体的吸波效率与吸波频带随着镧掺杂量的提高而改变;当镧掺入量x为0.15时,所得镧掺杂六角钡铁氧体/石蜡混合物具有良好的吸波性能：在厚度为2 mm时其最高吸收损耗达-15 d B,吸收损耗高于-10 d B的吸收频带为13-16 GHz,频带宽度为3 GHz。展开更多
Novel mono-dispersed hollow polyhedral ceria nano powders with the average particle size of 250 nm were directly synthesized via a simple template-free mixed solvothermal method by using water-ethanol as the solvent. ...Novel mono-dispersed hollow polyhedral ceria nano powders with the average particle size of 250 nm were directly synthesized via a simple template-free mixed solvothermal method by using water-ethanol as the solvent. The formation of such hollow structure with the regular polyhedral particle shape was based on a solvent-controlled Ostwald ripening coupled self-templating process. The mixed solvent promoted the formation of the regular solid particles at the beginning of solvothermal reaction and drove the Ostwald ripening as the reaction went on. Owing to the Ostwald ripening and self-assembly of nano crystallites, ceria nano particles converted into the hollow structures with regular polyhedral shape during the solvothermal process just by increasing solvothermal reaction time. The as-synthesized hollow ceria nano powders exhibited strong absorptions in the UV-vis spectrum and the evaluated energy band gaps increased according to the shape evolution and size decrease of the nano particles, which demonstrated obvious blue shift effects.展开更多
文摘目的:建立高效液相色谱-串联质谱法测定蜂王浆中草甘膦、氨甲基膦酸和N-乙酰草甘膦含量的分析方法。方法:样品经0.2mol/L碳酸氢铵水溶液提取,采用Waters PRIME HLB固相萃取小柱净化,以Dikma Polyamino HILIC色谱柱进行色谱分离,多反应监测(MRM)监测模式测定,外标法定量。结果:3种化合物在20~400μg/L的浓度范围内线性关系良好,检出限为20μg/kg,定量限位50μg/kg。空白蜂王浆样品的3水平加标回收率为74.0%~96.1%,相对标准偏差为5.1%~9.6%。结论:该方法适用于蜂王浆中草甘膦及其两种代谢物残留的检测。
文摘采用溶胶-凝胶自燃烧法合成镧掺杂六角钡铁氧体（LaxBa1-xFe12O19）纳米粉体,细致研究了镧掺杂量对所合成六角钡铁氧体纳米粉体物相形成、颗粒尺寸以及电磁特性等的影响。结果表明：随着镧掺杂量的提高,获得纯相掺杂铁氧体粉体的热处理温度提高,当热处理温度为1000℃时,所得纯相镧掺杂六角铁氧体粉体Ba位La掺杂量x（摩尔分数）可达0.20;镧元素掺杂抑制了后续热处理过程中晶粒长大,对于所合成产物的颗粒呈现出一定细化作用,这在较高热处理温度下更为明显;镧掺杂改性六角钡铁氧体的吸波效率与吸波频带随着镧掺杂量的提高而改变;当镧掺入量x为0.15时,所得镧掺杂六角钡铁氧体/石蜡混合物具有良好的吸波性能：在厚度为2 mm时其最高吸收损耗达-15 d B,吸收损耗高于-10 d B的吸收频带为13-16 GHz,频带宽度为3 GHz。
基金supported by the National Natural Science Foundation of China(51103125,51102073)China Postdoctoral Science Foundation(2015M570483)the Priority Academic Program Development of Jiangsu Higher Education Institutions(Chemistry)
文摘Novel mono-dispersed hollow polyhedral ceria nano powders with the average particle size of 250 nm were directly synthesized via a simple template-free mixed solvothermal method by using water-ethanol as the solvent. The formation of such hollow structure with the regular polyhedral particle shape was based on a solvent-controlled Ostwald ripening coupled self-templating process. The mixed solvent promoted the formation of the regular solid particles at the beginning of solvothermal reaction and drove the Ostwald ripening as the reaction went on. Owing to the Ostwald ripening and self-assembly of nano crystallites, ceria nano particles converted into the hollow structures with regular polyhedral shape during the solvothermal process just by increasing solvothermal reaction time. The as-synthesized hollow ceria nano powders exhibited strong absorptions in the UV-vis spectrum and the evaluated energy band gaps increased according to the shape evolution and size decrease of the nano particles, which demonstrated obvious blue shift effects.
