On the reproducibility of Chromolithe® RP columns

Monolithic columns are of growing importance in routine analysis. As all of these columns are solitaires, the reproducibility has been studied for the commercially available RP Chromolith column. The chromatographic test revealed that in respect of efficiency this column is equivalent a column (of identical length: 5 cm) packed with particles around 4 mum, however, the pressure drop corresponds to a column packed with particles around 10 mum. Per unit pressure drop about 6 times the plates are generated. Four Chromolith columns from different batches were compared in respect of efficiency and retention times. The plate numbers were 5330 with a RSD of 5%. The retention times varied less than 1.6%, corresponding to good batch to batch reproducibility as achieved in the preparation of bulk reversed phases. Because of the short column length and the relatively high linear velocities, data acquisition time has to be increased at least to 25 Hz to be able to fully exploid the potential efficiencies these columns are able to generate.