TOX 3300 Chapter Notes - Chapter 25: Volumetric Flow Rate, Partition Chromatography, Silanol
13 Nov 2017
School
Department
Course
Professor
Document Summary
High-performance liquid chromatography (hplc) uses high pressure to force solvent through closed columns containing fine particles that give high-resolution separations. Chromatographer generally choose gas chromatography over liquid chromatography when there is a choice, because gas chromatography is normally less expensive, yields greater separation efficiency, and generates much less waste. Liquid chromatography is important because many chemical, biochemical and pharmaceutical compounds are not sufficiently volatile for gas chromatography. Increasing the rate at which solute equilibrates between stationary and mobile phases increases the efficiency of chromatography. Diffusion in liquids is 104 times slower than diffusion in gases. Therefore, in liquid chromatography, it is not generally feasible to use open tubular columns, because the diameter of the solvent channel is too great to be traversed by a solute molecule in a short time. Liquid chromatography is conducted with packed columns so that a solute molecule does not have to diffuse very far to encounter the stationary phase.
