Identification of the factors that influence the reproducibility of chromatographic retention data

Principal component analysis was used to identify the parameters that influ ence the column-to-column and batch-to-batch reproducibility of retention t imes and retention factors measured on Symmetry C-18, Kromasil C-18, Luna C -18 (2) and Vydac RPC18, all reversed-phase silica columns. We devised a pr ocedure that allows the determination of the differences in column volume a nd packing density between two columns, provided that these columns are pac ked with identical stationary phases (i.e., phases that originate from the same batch). Principal component analysis of the retention times confirmed that the column-to-column variations of the column volume and the total por osity of the bed are the factors that influence the reproducibility of the retention times, the column volume being the major factor. For the fluctuat ions of the retention factors, the column phase ratios (nr the bed porositi es) and some specific, secondary retention mechanisms are responsible. All the C-18 columns investigated proved to behave in a very similar fashion. T wo principal components were always sufficient to characterize the variatio ns of either the: retention times or the retention factors. (C) 2001 Elsevi er Science B.V.,All rights reserved.