Chemical ionization mass spectrometry with NH3 as a reagent gas provides an excellent method for qualitative analysis of plant alkaloid mixtures. Plant alcoholic extracts are purified by a differential pH extraction to yield a crude alkaloid mixture which can then be analyzed by NH3/ci direct insertion probe mass spectrometry. Good quasimolecular ion (M+ 1) peaks are observable for individual alkaloid components of the mixture. The technique is shown to apply to analysis of plant extracts containing pyrrolizidine, quinolizidine, diterpenoid, bishordeninyl terpene, and indole alkaloids, but should be adaptable to any alkaloid mixture.