DETERMINATION OF INDOLE-3-PYRUVIC ACID LEVELS IN ARABIDOPSIS-THALIANABY GAS-CHROMATOGRAPHY SELECTED-ION MONITORING MASS-SPECTROMETRY

A rapid and simple method is described for the determination of indole -3-pyruvic acid (IPA) levels in Arabidopsis thaliana by gas chromatogr aphy-selected ion monitoring-mass spectrometry (GC-SIM-MS). The method includes derivatization of IPA with hydroxylamine in the crude extrac t, followed by ethyl acetate partitioning, solid-phase extraction with C-18 resin, reversed-phase high-performance liquid chromatography (HP LC), and GC-SIM-MS. Three derivatizing reagents were tested; these wer e pentafluorobenzylhydroxylamine, pentafluorophenylhydrazine, and hydr oxylamine. Hydroxylamine proved to be the most useful, as the TPA-oxim e was easiest to purify from plant extracts and was the most stable. I PA was quantified in Arabidopsis seedlings ranging in age from 5 to 12 days; levels varied from 4 to 13 ng/g, peaking at 7-9 days. (C) 1998 Elsevier Science B.V.