CHARACTERIZATION OF ABSCISIC-ACID AND METABOLITES BY COMBINED LIQUID-CHROMATOGRAPHY MASS-SPECTROMETRY WITH ION-SPRAY AND PLASMA-SPRAY IONIZATION TECHNIQUES

Liquid chromatographic-mass spectrometric methods have been developed for the characterization of abscisic acid (ABA) and metabolites in plant cell cultures using plasma-spray and ion-spray ionization techniques. Both techniques provide useful mass spectral data for ABA and its acidic metabolites. The most intense ions in these spectra are represented by [M + H]+ and [M + H - H2O]+. The limit of detection for ABA, using plasma-spray and ion-spray was 5 and 9 ng, respectively, for full scans and 0.5 and 1 ng, respectively, for selected-ion recording of m/z 265, the protonated molecular ion. Ion-spray also provided intense protonated molecular ions for the neutral ABA metabolites whereas plasma-spray did not. Spectra acquired using both techniques showed intense ions indicating the presence of the ABA moiety in these neutral conjugates.