IDENTIFICATION OF QUATERNARY AMMONIUM AND TERTIARY SULFONIUM COMPOUNDS BY PLASMA DESORPTION MASS-SPECTROMETRY

A rapid and sensitive method for the identification of quaternary ammo nium and tertiary sulfonium compounds is described, The method utilize s plasma desorption mass spectrometry (PDMS) in which a Cf-252 ionizin g source produces fission fragments which interact with the sample to yield ions which are then analyzed by a time-of-night mass spectromete r. The method was applied to analyses of authentic standards and to th e identification of quaternary ammonium and tertiary sulfonium compoun ds in higher plant leaf extracts purifed by ion-exchange chomatography . Plant species from 14 different families were tested, including spec ies which are known glycinebetaine, beta-alaninebetaine, prolinebetain e or beta-dimethylsulfoniopropionate accumulators. PDMS results confir med and extended the known taxonomic distributions of these compounds. Glycinebetaine was found in one species Kra meria parvifolia from a f amily (Krameriaceae) not previously known to accumulate this compound. Pipecolatebetaine was identified in Achillea filipendulina (Asteracea e). The occurrence of prolinebetaine and hydroxyprolinebetaine(s) was confirmed in three species (Lamium maculatum, Stackys byzantina and Ph lomis fraticosa) of the tribe Lamieae of the subfamily Lamioideae in t he family Lamiaceae, but not in a fourth member of this tribe (Physost egia viugirtiana). The last species accumulated only trigonelline. The PDMS method was also used to identify trigonelline-deficient Zea mays lines.