Verification of retention and zone spreading equations in sedimentation field flow fractionation
Verification of retention and zone spreading equations in sedimentation field flow fractionation
复制标题
沉降场流分级中保留和区域扩散方程的验证
DOI：
10.1021/ac00232a005
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发表时间：
1981
影响因子：
7.4
通讯作者：
J. Giddings
中科院分区：
文献类型：
--
作者：
G. Karaiskakis;M. N. Myers;K. Caldwell;J. Giddings
有人认为，复杂的颗粒和大分子群体的准确表征场流分级（FFF）铰链，在很大程度上，在FFF理论和experimentary之间的协议保留和区域扩展。在简要回顾过去的理论和实验比较，我们总结了相关的理论方程。两个沉降FFF系统进行了描述，并提出了聚苯乙烯乳胶珠，据推测，以及其特点的结果。在保留测量和理论上，一些样品非常接近（~ 1%）的一致性与存在严重差异的情况形成强烈对比。据认为，差异是由于不准确的规格颗粒直径。区域扩展（板高度）测量证实了这一点，证明与保留测量相当一致，但与一些报告的直径不一致。结果表明，理论与实验符合得很好场流分级（FFF）的分析优势之一是分离发生在这样简单几何形状的通道中，在该通道内存在这样均匀分布的流，可以开发出将这些组分的保留和区域扩展与基本物理化学参数相关联的精确方程。那么，可以推测，在FFF通道中溶质行为的测量可以用于推断这些物理化学参数，从而帮助表征或识别溶质材料。因此，重要的是要确定的理论和实验之间的协议在FFF的接近程度，以评估该程序的潜在准确性。因此，已经通过使用FFF的各种子技术进行了许多保留和区域扩展的研究（1-8）。一般来说，保留方程已经得到很好的验证，通常精确到几个百分点。区带扩展测量比保留测量具有更大的相对不确定性。在之前最细致的研究中，在11个不同的热FFF通道中使用线性聚苯乙烯聚合物，与理论的偏差平均约为30%（8）。沉降FFF，使用聚苯乙烯乳胶珠作为样品探针，似乎是一个理想的组合，以测试理论和实验之间的协议。这样的珠在电子显微镜测量中用作标准，并且必要的尺寸、密度和多分散性参数可从制造商获得。早期使用这种微珠的实验验证了FFF保留方程的适用性，但在区域扩展方面遇到了很大的差异（2）。在这项研究中，我们将重新确认保留研究，然后试图提高区带扩展测量的准确性水平，可以与理论进行有意义的比较。
It Is argued that accurate characterization of complex particle and macromolecule populations by field-flow fractionation (FFF) hinges, in large part, on the agreement between FFF theory and experimentwith respect to retention and zone spreading. After briefly reviewing past comparisons of theory and experiment, we summarize the relevant theoretical equations. Two sedimentation FFF systems are described and results are presented for polystyrene latex beads that are presumably well characterized. Very close (~ 1%) agree-ment In retention measurements and theory for some samples contrasts strongly with cases having serious discrepancies. It Is suggested that the discrepancies are dueto the inaccurate specifications given for particle diameters. The zone spreading (plate height) measurements verify this, demon-strating rather uniform consistency with the retention mea-surements but not with some reported diameters. It Is con-cluded that theory and experiment agree very well (a few percent) for retention parameters and within 5-10% for plate height parameters.One of the analytical strengths of field-flow fractionation (FFF) is that separation occurs in a channel of such simple geometry, within whichthere is flow of such uniform profile, that exact equations can be developed relating such compo-nent’s retention and zone spreading to underlying physicochemical parameters. Presumably, then, the measurement of a solute’s behavior in an FFF channel can be used to deduce these physicochemical parameters, thushelping characterize or identify the solute material. It is therefore important to determine the closeness of the agreement between theory and experiment in FFF to assess the potential accuracy of this procedure. Consequently, a number of studies of retention and zone spreading have been made by using various sub-techniques of FFF {1-8). Generally, the retention equations have been well verified, often accurate to within a few percent. Zone spreading méasurements are subject to larger relative uncertainties than retention measurements. In the most meticulous of previous studies, using linear polystyrene polymers in 11 different thermal FFF channels, the departure from theory averaged approximately 30%(8). Sedimentation FFF, using polystyrene latex beads as sample probes, would appear to be an ideal combination to test the agreement between theory and experiment. Such beads are used as standards in electron microscope measurements and the necessary size, density, and polydispersity parameters are available from the manufacturer. Earlier experiments with such beads verified the applicability of the FFF retention equations but encountered large discrepancies in zone spreading (2). In this study we will reconfirm the retention studies and then attempt to improve zone spreading mea-surements to a level of accuracy where meaningful comparisons with theory can be made.