Particle size distribution by sedimentation/steric field-flow fractionation: development of a calibration procedure based on density compensation.
Particle size distribution by sedimentation/steric field-flow fractionation: development of a calibration procedure based on density compensation.
复制标题
通过沉降/空间场流分级进行粒度分布：开发基于密度补偿的校准程序。
DOI：
10.1021/ac00014a006
复制
发表时间：
1991
影响因子：
7.4
通讯作者：
Myers,MN
中科院分区：
文献类型：
--
作者：
Giddings,JC;Moon,MH;Williams,PS;Myers,MN
由于流体动力学升力在沉降/空间FFF中所起的重要但数学上复杂的作用，通常应用于直径> 1 μ m的颗粒，因此不能根据简单的理论将滞留与颗粒直径联系起来。因此，需要进行经验校准。不幸的是，保留是基于颗粒密度以及尺寸，因此纯粹基于尺寸的校准（例如，使用聚苯乙烯乳胶标准品）通常是无效的。通过检查驱动力和升力之间的平衡，可以得出结论，对于受到相同驱动力的相同尺寸的颗粒，无论颗粒密度如何，都将观察到相同的保留。因此，通过调整旋转速率以精确补偿密度，可以使保留与标准品一致，这一结论通过显微镜验证。然后可以使用log（保留时间）与log（直径）的线性校准图。使用传统入口通道和挤压入口通道，将这种方法应用于两个玻璃珠样品（5-30和5-50 pm）。所得的粒度分布曲线是自洽的，与独立获得的结果一致。场流分级（FFF）由许多操作模式和子技术组成，每一种都有其独特的特点和适用范围（1-3）。例如，FFF的正常模式，无论所施加的场是沉降场、热场、横流场还是电场，都适用于直径高达约1 μ m的大分子和颗粒，或者在特殊情况下，适用于粒径高达3 μ m或4 μ m的大分子和颗粒。在正常模式下，保留对颗粒尺寸或质量的依赖性通常是相当可预测的，只要所施加的场施加在样品颗粒上的力是可计算的量（2）。例如，在沉降FFF的正常模式下，对于已知尺寸和密度的颗粒，可以根据第一原理以合理的精度计算保留时间（4）。因此，可以获得颗粒尺寸分布
Because of the Important but mathematically complex role played by hydrodynamic lift forces In sedimentation/steric FFF, applied generally toparticles> 1 pm In diameter, re-tention cannot readily be related to particle diameter on the basis of simple theory. Consequently, empirical calibration Is needed. Unfortunately, retention Is based on particle den-sity as well as size so that a purely size-based calibration (eg, with polystyrene latex standards) Is not generally valid. By examining the balance between driving and lift forces, it Is concluded that equal retention will be observed for equal size particles subject to equal driving forces Irrespective of particle density. Therefore by adjusting the rotation rate to exactly compensate for density, retention can be brought In line with that of standards, a conclusion verified by microscopy. Linear calibration plots of log (retention time) versus log (diameter) can then be used. This approach Is applied to two glass bead samples (5-30 and 5-50 pm) using both a conventional and a pinched Inlet channel. The resulting size distribution curves are self consistent and In good agreement with results obtained Independently.Field-flow fractionation (FFF) consists of a great number of operating modes and subtechniques, each having its own unique characteristics andrange of applicability (1-3). For example, the normal mode of FFF, whetherthe applied field is sedimentation, thermal, crossflow, or electrical, is applicable to macromolecules and particles up to about 1 pm in diameter, or in special circumstances up to 3 or 4^ im particle size. The dependence of retention on particle size or mass in the normal mode is generally quite predictable, providing the force exerted on the sample particles by the applied field is a calculable quantity (2). In the normal mode of sedimentation FFF, for example, the retentiontime can be calculated with reasonable accuracy from first principles for particles of known size and density (4). Thus particle size distributions can be obtained