Comparative study on the column performance of microparticulate 5-μm C 18-bonded and monolithic C 18-bonded reversed-phase columns in high-performance liquid chromatography

Abstract

In this paper we report on the results of a comparative study on the performance of Purospher RP 18e, 5 μm, columns and prototypes of monolithic columns named SilicaROD from Merck, Darmstadt, Germany. The studies were performed on HPLC equipment with minimum extra column contribution. The plate height linear velocity dependency of the Purospher RP 18e column showed a minimum of H of about 10–15 μm at a linear velocity of 1 mm/s. The H versus u curves of the monolithic columns followed the same course. Yet, the curves remained flat up to a linear velocity of about 7 mm/s, where the Purospher RP 18e column could not be operated anymore due to the extremely high back-pressure. In conclusion the monolithic HPLC columns showed a column performance equivalent to a column with about 5 μm porous particles and were operated at flow-rates up to 9 ml/min on a conventional HPLC equipment without notable loss in column efficiency. The column back-pressure drop at the monolithic columns was three- to five-times lower than that on the 5-μm particulate column.