Miniaturized HPLC and ionspray mass spectrometry applied to the analysis of Paclitaxel and taxanes

Analysis of the antitumor agent Paclitaxel, related taxane analogues and yew tree bark extracts has been carried out ming an HPLC system capable of performing chromatographic separations with conventional, small-bore, and micro-bore columns. Both diode array detector and mass spectrometry were incorporated into this system, providing additional spectral and structural information for identification of unknown samples. In conjunction with some basic theoretical studies dealing with miniaturized HPLC systems, experiments were designed to minimize the contribution of extra-column variances. Three chromatographic columns, 4.6, 2, and 1 mm i.d., were evaluated using a standard mixture consisting of Paclitaxel and three analogues. The experimental results obtained in these columns demonstrated good correlation with theoretical calculations with respect to the sensitivity enhancement. Studies on the combination of miniaturized HPLC with ionspray mass spectrometry for Paclitaxel samples showed dramatic improvement of MS performance as compared to conventional LC/MS. The advantages of this miniaturized LC/MS system are evidenced by enhanced mass sensitivity, which was more than two order of magnitude higher when changed from a 4.6 mm i.d. column to a 2.0 mm i.d. column, greatly improved peak shape, and the potential gain of efficiency. These studies demonstrate great potential of miniaturized HPLC/MS systems for structural characterization and confirmation of various pharmaceutical compounds. (C) 1997 Elsevier Science B.V.