DETERMINATION OF VINCRISTINE AND VINBLASTINE IN CATHARANTHUS-ROSEUS PLANTS BY HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY ELECTROSPRAY-IONIZATION MASS-SPECTROMETRY

A reversed phase high performance liquid chromatographic/mass spectrom etric (LC-MS) method with an electrospray ion source was used in this study to determine the concentration of two dimeric alkaloids, vinblas tine and vincristine, in near-isogenic lines of Catharanthus leaves. A linear gradient of 25 mM ammonium acetate in methanol (solution A) an d the same concentration in water (solution B) served as the mobile ph ase. A C-18 column was used to separate those two compounds from other components in the extracted plant samples. Mass spectra generated by the electrospray ionization source were dominated by protonated molecu les with little or no fragmentation being observed under the experimen tal conditions applied. Since very little fragmentation occurred, the method exhibited enhanced sensitivity over other LC-MS techniques. Pro duct-ion mass spectra of vincristine and vinblastine were produced in a single quadrupole mass spectrometer through collision-induced dissoc iation (CID) between the capillary exit and first skimmer of the elect rospray source. CID spectra can be used to unequivocally differentiate between vincristine, vinblastine and other alkaloids.