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

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