排序方式: 共有20条查询结果,搜索用时 15 毫秒
1.
2.
枪头式分散固相微萃取柱方法结合气相色谱-串联质谱测定果蔬中9种农药多残留 总被引:1,自引:0,他引:1
目的建立枪头式分散固相微萃取柱(disposable pipette extraction, DPX)结合气相色谱-串联质谱法同时测定番茄、苹果、小青菜3种水果蔬菜中的9种农药残留的方法。方法水果蔬菜样品经均质,乙腈抽提,采用DPX-RP枪头式分散固相微萃取柱进行净化。采用气相色谱-串联质谱法-多反应模式监测(multiple reaction monitoring, MRM)测定,内标法定量。结果9种农药化合物在10~800μg/kg浓度范围内呈现良好的线性关系,相关系数均大于0.995,方法的检出限为0.3~4.7μg/kg,定量限为1.2~13.5μg/kg。分别在番茄、苹果、小青菜中添加水平为50、250、500μg/kg的混标,平均回收率为72.8%~115.9%,方法的相对标准偏差(relative standard deviation, RSD)为0.29%~9.9%,通过与DPX多通道半自动前处理仪结合使用可在10 min内净化处理1~48个样品,有效缩短了样品前处理的时间。结论本方法简便、省时,并且高通量,适用于水果蔬菜中农药残留的测定。 相似文献
3.
4.
5.
Murat Kademli 《Particulate Science and Technology》2013,31(4):326-331
This investigation is concerned with the comparison of the advantages and disadvantages of subsieving techniques widely used in mineral processing throughout the world. With this purpose, the subsieving techniques of Andreasen pipette, Coulter counter, and laser diffraction methods were compared each other by determining the relationship between specific surface area and particle size distribution. In the tests, the two different standard quartz sand samples (A and B) from the Official Material Testing Institute for Nonmetallic Minerals, Clausthal-Zellerfeld with a particle density of ρ = 2.65 g/cm3 were used. As a result, the Coulter counter method had the most favorable results in terms of calculated specific surface areas of 3848 cm2/g for sample A and 2852 cm2/g for sample B, with standard deviations 41.29 and 32.48, respectively. 相似文献
6.
A convective assembly technique at the micron scale analogous to the writing action of a “pipette pen” has been developed
for the linear assembly of gold nanoparticle strips with micron scale width and millimeter scale length for surface enhanced
Raman scattering (SERS). The arrays with interparticle gaps smaller than 3 nm are hexagonally stacked in the vicinity of the
pipette tip. Variable numbers of stacked layers and clean surfaces of the assembled nanoparticles are obtained by optimizing
the velocity of the pipette tip. The SERS properties of the assembled nanoparticle arrays rely on their stacking number and
surface cleanliness.
相似文献
7.
土体的粒度成分在土体的定名、鉴别、描述及预测土体工程性质上具有重要应用。为了研究非饱和土体粒度成分的测量方法及测量结果,本文分别采用密度计法、移液管法和激光粒度仪法对合肥地区9种非饱和膨胀土进行了粒度测量,得到了相应的粒径分布,并采用 Fredlund模型进行了曲线拟合,得到了试验土体的粒径分布曲线(PSD ),求得了相应的曲线拟合参数的均值、均方差及变异系数。在此基础上,对3种测量方法的PSD曲线拟合参数进行了回归分析,求得了激光法的PSD拟合参数与传统的密度计法及移液管法的PSD拟合参数间的相关关系。 相似文献
8.
9.
10.
Sunil Chhatre Nigel J. Titchener‐Hooker 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2009,84(7):927-940
Demands within the pharmaceutical sector to cut costs and improve process efficiencies have grown considerably in recent years. Major challenges exist for companies trying to establish financially viable and robust manufacturing processes for increasingly complex therapeutics. These issues have driven the investigation of miniaturised process‐design techniques by which to identify suitable operating conditions using small volumes of feed material typical of that available in the early stages of bioprocess development. Such techniques are especially valuable for the optimisation of chromatographic separations, which often represent a significant percentage of manufacturing costs and hence for which there is a pressing need to determine the best operating policies. Several methods employing microlitre volumes of sample and resin have been explored recently, which are aimed at the high‐throughput and cost‐effective exploration of the design space for chromatographic separations. This methodology paper reviews these microscale approaches and describes how they work, gives examples of their application, discusses their advantages and disadvantages and provides a comparative assessment of the different methods, along with a summary of the challenges that remain to be overcome in relation to these techniques. Copyright © 2009 Society of Chemical Industry 相似文献