Laboratory to Laboratory Reproducibility of High Performance Liquid Chromatographic Retention Indices

Using seven typical drugs, the intra-and inter-laboratory reproducibility of the measured HPLC retention indices, relative retention times, and adjusted relative retention times using the same mobile phase and various reversed-phase C-18 columns were determined. Within a given laboratory, the respective relative standard deviations were ± 0.99%, ± 1.78%, and ± 2.63%. Between laboratories, the respective relative standard deviations were found to be ± 12.6%, ± 30.2%, and ± 34.8%. These results indicated that the HPLC retention index scale may be more useful in comparing data between laboratories.