Fingerprint development for Ginkgo biloba extracts by pressurized capillary electrochromatography: comparison of column types.

A pressurized capillary electrochromatographic (pCEC) fingerprint of Ginkgo biloba leaf extract was developed on three different types of capillary columns. A commercial column packed with 3-microm particles and an in-house column packed with 5-microm particles were investigated for their performance. Additionally, a monolithic column was included in the fingerprint study as a potential alternative to the conventional packed columns. The effects of experimental parameters, such as the composition of the mobile phase, the concentration and pH of the buffer, and the applied voltage, were studied. Binary mobile phases consisting of acetonitrile and a 5 mM sodium dihydrogen phosphate electrolyte at pH 2.8 were used in gradient elution mode with an applied voltage of 5 kV. Under optimal gradient conditions, at least 45 peaks were observed within 60 min on the commercial packed column, whereas only about 20 peaks were separated on the methacrylate-based monolithic and the in-house packed columns. The commercial column thus clearly outperforms the two other. However, the properties of the monolithic stationary phase still might be adapted (i.e., by changing the polymerization-mixture composition, the porosity, and thus the selectivity of the phase might be changed), which could lead to an improved efficiency.