Liquid Chromatographic Preparative Packing Utility as a Function of Particle Shape

Abstract

Abstract The “equal-cut-point” approach (12) has been applied to comparing the relative utilities for preparative liquid chromatography of five irregular and three spherical packings. Packed with these, the variation of peak width with loading was first established and plotted, for columns of given length. From these plots, the loading that produced a given peak width was found for each column. The packings then received purely technical ratings, taken as the ratios of these loadings to the minimum loading observed. The three highest purely technical ratings-without regard to packing cost-were attained by the 5-micron irregular (4·72), the 10-micron irregular (4·04), and the 10-micron spherical (3·09). To express value (that is, performance per cost), the technical ratings were divided by the costs of the packings. The most valuable packings were found to be, first, the 10-micron irregular, value 9·45; second, the 40-micron irregular, value 7·01; third, the 20-micron irregular, value 6·54; and fourth, the 5-micron irregular, value 5·20. The irregular packings showed much more value than the spherical-the fourth-ranking 5-micron irregular at 5·20 was almost 3 times more valuable than the best of the sphericals, the 10-micron, at 1·78. This study was conducted under mass overload; at the end of the paper, volume overload is shown as inherently unsuited for such studies.