University of Ottawa, Department of Physics, MacDonald Hall, 150 Louis-Pasteur, Ottawa, ON, K1N 6N5, Canada.
J Chromatogr A. 2012 Apr 13;1233:100-8. doi: 10.1016/j.chroma.2012.01.061. Epub 2012 Jan 30.
Through a careful consideration of the retention ratio for field-flow fractionation (FFF), we show that a single unified ideal retention theory can predict a wide range of separation behaviours including hydrodynamic chromatography, normal-mode FFF and steric-mode FFF by introducing the concept of a device retention parameter. We determine the critical device retention parameter above which normal-mode does not exist and there is no clear distinction between hydrodynamic chromatography and steric-mode FFF. Numerical analysis of the elution order as a function of particle size quantitatively predicts the transitions between these regimes. The resulting map of the operational-modes shows each of the regions and their connectivity, and so may guide future device design. By extending this analysis to account for the variation of stress over particle surfaces, a hitherto unreported regime called Faxén-mode FFF is predicted, which has the same elution order as normal-mode FFF. This mode arises when particle sizes approach the channel height, as can occur when microfluidic devices are utilized for FFF. The transition from steric-mode to Faxén-mode FFF is numerically mapped and approximations for each transition are presented.
通过对场流分级（FFF）的保留率进行仔细考虑，我们通过引入设备保留参数的概念，展示了单一的统一理想保留理论可以预测广泛的分离行为，包括流体力学色谱、常规模式 FFF 和空间排阻模式 FFF。我们确定了临界设备保留参数，超过该参数后，常规模式将不复存在，并且流体力学色谱和空间排阻模式 FFF 之间也没有明显的区别。作为粒径函数的洗脱顺序的数值分析定量预测了这些区域之间的转变。所得的操作模式图显示了各个区域及其连接性，因此可以指导未来的设备设计。通过将这种分析扩展到考虑颗粒表面上的应力变化，可以预测到一种迄今为止尚未报道的称为 Faxén 模式 FFF 的模式，其洗脱顺序与常规模式 FFF 相同。当颗粒尺寸接近通道高度时，会出现这种模式，这在使用微流控设备进行 FFF 时可能会发生。对从空间排阻模式到 Faxén 模式 FFF 的转变进行了数值映射，并提出了每个转变的近似值。
