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Lijun He Chunjian Wang Yinjuan Sun Xianli Luo Jing Zhang Kui Lu 《International journal of environmental analytical chemistry》2013,93(6):439-448
A simple, rapid and efficient method, dispersive liquid–liquid microextraction (DLLME) in conjunction with high-performance liquid chromatography (HPLC), has been developed for the determination of three carbamate pesticides (methomyl, carbofuran and carbaryl) in water samples. In this extraction process, a mixture of 35 µL chlorobenzene (extraction solvent) and 1.0 mL acetonitrile (disperser solvent) was rapidly injected into the 5.0 mL aqueous sample containing the analytes. After centrifuging (5 min at 4000 rpm), the fine droplets of chlorobenzene were sedimented in the bottom of the conical test tube. Sedimented phase (20 µL) was injected into the HPLC for analysis. Some important parameters, such as kind and volume of extraction and disperser solvent, extraction time and salt addition were investigated and optimised. Under the optimum extraction condition, the enrichment factors and extraction recoveries ranged from 148% to 189% and 74.2% to 94.4%, respectively. The methods yielded a linear range in the concentration from 1 to 1000 µg L?1 for carbofuran and carbaryl, 5 to 1000 µg L?1 for methomyl, and the limits of detection were 0.5, 0.9 and 0.1 µg L?1, respectively. The relative standard deviations (RSD) for the extraction of 500 µg L?1 carbamate pesticides were in the range of 1.8–4.6% (n = 6). This method could be successfully applied for the determination of carbamate pesticides in tap water, river water and rain water. 相似文献
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通过三维动力学有限元法,以空间杆单元模拟缝线的增强作用,建立了缝合复合材料层板在横向低速冲击载荷作用下的渐近损伤分析模型.该模型考虑了缝合层板受低速冲击时的纤维断裂、基体开裂及分层等五种典型损伤形式,采用基于应变描述的Hashin失效准则和Yeh分层失效准则,并将其嵌入ABAQUs/Explicit用户子程序以实现相应损伤类型的判断及其材料性能退化.针对相同铺层的缝合与未缝合层板,模拟了低速冲击作用下的冲击响应和渐进损伤过程,数值结果与试验吻合较好,证明了该方法的合理有效性.同时探讨了冲击速度、缝合密度等对缝合层板冲击响应和损伤的影响. 相似文献
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为了解南通市患儿体内微量元素锌、铅含量及其关系,采用火焰原子吸收分光光度法对1 118例发锌、铅进行了检测分析,按性别、年龄做了锌、铅的相关分析。结果表明,缺锌率为77.91%;铅含量均在正常范围内;南通市患儿锌、铅的x-±s分别为(83.6±24.8)、(1.4±0.7)μg/g;低锌和低铅污染无负相关关系。 相似文献
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Ma CH Liu TT Yang L Zu YG Chen X Zhang L Zhang Y Zhao C 《Journal of chromatography. A》2011,1218(48):8573-8580
Ionic liquid-based microwave-assisted extraction (ILMAE) has been successfully applied in extracting essential oil and four kinds of biphenyl cyclooctene lignans from Schisandra chinensis Baill. 0.25 M 1-lauryl-3-methylimidazolium bromide ionic liquid is selected as solvent. The optimum parameters of dealing with 25.0 g sample are 385 W irradiation power, 40 min microwave extraction time and 1:12 solid-liquid ratio. The yields of essential oil and lignans are 12.12±0.37 ml/kg and 250.2±38.2 mg/kg under the optimum conditions. The composition of the essential oil extracted by hydro-distillation, steam-distillation and ILMAE is analyzed by GC-MS. With ILMAE method, the energy consumption time has not only been shortened to 40 min (hydro-distillation 3.0 h for extracting essential oil and reflux extraction 4.0 h for extracting lignans, respectively), but also the extraction efficiency has been improved (extraction of lignans and distillation of essential oil at the same time) and reduces the environmental pollution. S. chinensis materials treated by different methods are observed by scanning electronic microscopy. Micrographs provide more evidence to prove that ILMAE is a better and faster method. The experimental results also indicate that ILMAE is a simple and efficient technique for sample preparation. 相似文献
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改变检测波长高效液相色谱法测定喜树碱和羟基喜树碱的含量 总被引:10,自引:0,他引:10
建立了改变检测波长测定喜树种子中喜树碱和 10 羟基喜树碱的高效液相色谱法。使用TechspheseODSC18(4.6mm× 2 5cm ,5 μm)色谱柱 ,以水∶乙腈 =3∶7(V/V)为流动相 ,流速为 1.0mL/min ,2 5℃下检测。检测波长 :0~ 8min时为 2 6 6nm ,8~ 2 0min时为 2 5 4nm。结果表明 :喜树碱的平均回收率为 10 0 .92 % ,RSD值 1.4 0 % ;羟基喜树碱的平均回收率为 10 0 .0 9% ,RSD值 1.34%。此方法简单、可靠。 相似文献
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研究了盐酸介质中,痕量亚硝酸根催化溴酸钾氧化中性红褪色反应及其动力学条件,建立了催化动力学光度法测定痕量亚硝酸根的新方法,NO^-2的测定线性范围为1-7μg/25ml,检出限为1.5*10^-8g.ml^-1。用于化学试剂及唾液中痕量NO^-2的测定,结果满意。 相似文献
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Yunxing Li Zhen Zhao Chunjian Wang Cheng Yang Zhaoqun Wang 《Colloid and polymer science》2013,291(5):1287-1291
By virtue of a smartly designed strategy, we successfully prepared the α-Fe2O3/carbon and electromagnetic polyhydroxy iron cation/polyaniline (PIC/PANi) hollow particles. First, poly(styrene-butyl acrylate)/polyhydroxy iron cation (P(S-BA)/PIC) composite particles were prepared based on electrostatic attraction between the P(S-BA) and PIC. Second, the coating of P(S-BA)/PIC composite particles with PANi was achieved by the “Swelling–Diffusion–Interfacial-Polymerization Method”. Finally, α-Fe2O3/carbon and PIC/PANi hollow particles were obtained by calcination or solvent extraction of the P(S-BA)/PIC/PANi composite particles, respectively. The whole preparation process was monitored by transmission electron microscope, scanning electron microscope, Fourier transform infrared, and X-ray diffraction. The synthesized α-Fe2O3/carbon and PIC/PANi hollow particles possessed of a narrow size distribution and well-defined morphology. 相似文献
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Y Li Z Wang C Wang Y Pan H Gu G Xue 《Langmuir : the ACS journal of surfaces and colloids》2012,28(35):12704-12710
The design and fabrication of functional nanocomposites is an active area of research because composite particles have significantly improved physical and chemical properties over those of their single-component counterparts. Traditionally, chemical pretreatments of the components were used to enhance their physicochemical or chemical interactions. Here, we propose a novel approach to taking advantage of the beauty of thermodynamics. A series of functional materials, including graphene nanosheets, carbon nanotubes, noble metals, magnetic materials, conducting polymers, attapulgite, and etc. were incorporated with polystyrene particles by a thermodynamic driving force. This unique approach is facile and versatile and shows the considerable significance of developments in both scientific methodology and particle engineering. 相似文献