Simplified nonequilibrium theory of secondary relaxation effects in programmed field-flow fractionation.
Simplified nonequilibrium theory of secondary relaxation effects in programmed field-flow fractionation.
复制标题
程序化场流分级中二次弛豫效应的简化非平衡理论。
DOI：
10.1021/ac00295a018
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发表时间：
1986
影响因子：
7.4
通讯作者：
Giddings,JC
中科院分区：
文献类型：
--
作者：
Giddings,JC
本文叙述了场流分馏中的主弛豫效应和次弛豫效应。结果表明，二次弛豫过程Incubation导致偏离稳态迁移时，使用现场编程。为了以简单的方式处理这个相当复杂的现象，非平衡理论已经被应用。用这种方法，一阶approximations已获得的偏离平衡的浓度在整个通道。在此之后，已推导出颗粒迁移速率、保留时间和衍生的物理化学性质（如颗粒质量）的相应增量的校正项。这些修正对于FFF的任何子技术的平衡偏差都是有效的，并提供了平衡偏差大小的简单判据。场流分馏（FFF）的基本机制是在FFF流道的积聚壁附近形成薄的颗粒云。当气流在通道中开始流动时，云以大致与云厚度l成比例的速度向下游移动。由于不同大小和类型的颗粒形成不同厚度的云，因此不同种类的颗粒的下游位移速度不同，从而确保分离。这种基本的分离机制已经被阐述了很多次，在此不再详述（1-3）。在本文中，我们专注于在云内的粒子分布的变化，由于不断变化的条件，特别是在整个通道中施加的场的强度的变化引起的。在跑步过程中的内场强度变化构成了场编程FFF的基础（4，5）。
Primary and secondary relaxation effects In field-flow frac-tionation are described. It is shown that secondary relaxation processes Invariably cause a departure from steady-state migration when field programming is used. To treat this rather complicated phenomenon In a simple manner, nonequilibrium theory has been applied. With this approach, first-order ap-proximations have been obtained for the departure from equilibrium of the concentration across the channel. Following this, correction terms have been derived for the corresponding Increments in particle migration rate, retention time, and de-rived physicochemical properties such as particle mass. These corrections are valid for small departures from equi-librium for any subtechnique of FFF and provide a simple criterion for the magnitude of equilibrium departure.The basic mechanism of field-flow fractionation (FFF) entails the formation of a thin cloud of particles near the accumulation wall of the FFF flow channel. When flow is initiated inthe channel, the cloud is displaced downstream at a velocity roughly proportional to the cloud thickness, l. Since particles of different sizes and types form clouds of different thicknesses, the downstream displacement velocities differ for different kinds of particles, thus ensuring separation. This basic mechanism of separation has been elaborated many times and will not be further detailed here (1-3). In this paper we focus on changes that are induced in the distribution of particles within a cloud due to changing con-ditions, particularly changes in the strength of the field applied across the channel. Changes infield strength inthe course of a run constitute the basis of field-programmed FFF (4, 5).
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影响因子：
6.2
作者：
D. Glick
通讯作者：
D. Glick
影响因子：
4.4
作者：
J. Giddings
通讯作者：
J. Giddings
色谱的物理化学基础
影响因子：
3
作者：
J. Giddings
通讯作者：
J. Giddings
影响因子：
7.4
作者：
J. Giddings;K. Caldwell;J. F. Moellmer;T. H. Dickinson;M. N. Myers;Michel Martin
通讯作者：
Michel Martin
影响因子：
7.4
作者：
Giddings,JC
通讯作者：
Giddings,JC