Comparative study on the column performance of microparticulate 5-μm C18-bonded and monolithic C18-bonded reversed-phase columns in high-performance liquid chromatography

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 th…

Rational design, tailored synthesis and characterisation of ordered mesoporous silicas in the micron and submicron size range

Evaluation and comparison of the pore structure and related properties of particulate and monolithic silicas for liquid phase separation processes

Two types of silicas, highly porous beads of 10 μm average particle diameter and particle porosity between 48 to 86 % and monolithic silicas with constant mesopore diameter of 12 nm, constant total porosity of 80 % at variable macropore diameter between 2 and 6 μm were subjected to pore structural characterisation and tests in high performance liquid chromatography (HPLC). The column permeability KF of the columns packed with highly porous beads was twice as much as for the monolithic silica columns. The differences in theoretical plate height - linear velocity curves could be explained on the basis of the pore connectivity values nT of the materials which were computed from the nitrogen so…