Field-Flow Fractionation (FFF) as an Integral Experiment in Junior Physical Chemistry Labs

本项目将场流分馏（FFF）纳入物理化学实验室。作为一种分离和表征直径从0.002到100微米的大分子和颗粒的方法，这种相对较新的技术正在迅速获得认可。该方法表面上类似于色谱法，但在FFF中分离的基础是颗粒沿通道流动与垂直于流动方向的外场的相互作用。分离的发生是由于颗粒的不同倾向，它们被迫进入靠近通道壁的缓慢载流子流线。FFF不仅是一种有前途的新技术，也是向学生介绍输运性质实验研究的理想工具。例如，在正流式FFF中，被洗脱颗粒的保留时间取决于该颗粒的扩散常数。已经对大分子和其他颗粒在0.002到1微米的宽范围内进行了扩散测量。本项目采用FFF扩散常数测量作为初级物理化学实验室的主要非平衡成分。它加入了表征多孔固体的实验，电化学测量活度系数，确定燃烧或溶液的焓，并建立化学反应的速率常数。此外，拟议的FFF实验也补充了这些练习与一个是计算机控制的。＊

This project incorporates field-flow fractionation (FFF) into the physical chemistry laboratory. This relatively new technique is rapidly gaining acceptance as a method for separating and characterizing macromolecules and particles with diameters ranging from 0.002 to 100 micrometers in diameter. The method is superficially similar to chromatography, but the basis of separation in FFF is the interaction of particle flow down a channel with an external field applied perpendicular to the direction of flow. Separation occurs because particles differ in their tendency to be forced into slow carrier streamlines adjacent to the channel wall. Besides being a new and promising technique, FFF is an ideal vehicle for introducing students to an experimental investigation of transport properties. For example, in normal mode flow FFF, the retention time of an eluted particle depends on the diffusion constant of that particle. Diffusion measurements have been made for macromolecules and other particles over the wide range of 0.002 to 1 micrometer. This project adopts FFF diffusion constant measurement as the primary nonequilibrium component of the junior-level physical chemistry laboratory. It joins experiments that characterize porous solids, measure activity coefficients electrochemically, ascertain enthalpies of combustion or solution, and establish rate constants of chemical reactions. Addition of the proposed FFF experiment also complements these exercises with one that is computer controlled. *