Wednesday, September 14, 2011
How Do C18 HPLC Phases Differ ?
Reversed phase HPLC columns which utilize the octadecyl functional group often differ in many ways. Besides the particle size, shape of the stationary phase (irregular or spherical), the coating chemistry and end-capping used. Two other very important ways that columns can differ from one another are in their available surface area and the extent to which those surfaces are covered with the phase coating (i.e. covalently bonded, non-covalently coated and the total carbon %). When comparing columns for use in validated methods, be sure and consider these factors to minimize the number of changes to your method. Always test several columns of the same type to determine the batch to batch reproducibility and variation. Some manufacturers have mastered the art of preparing and packing columns which achieve high batch to batch reproducibility. After all, what good is a column in your method if the results are not reproducible when you purchase another column some time later?