Methane chemical ionization mass spectrometry of the pentafluorobenzyl derivatives of abscisic acid, its metabolites and other plant growth regulators

Abstract

Tetraethyl ammonium hydroxide has been used as a catalyst for the pentafluorobenzylation of abscissic acid and its metabolites, as well as zeatin, gibberellic acid and indole acetic acid. These derivatives, acetylated where necessary, were subjected to methane negative ion chemical ionization mass spectrometry. The spectra were quite simple and are therefore ideally suited for selected ion monitoring at high sensitivity with heavy isotope labelled internal standards. The sensitivity for pentafluorobenzyl abscisate was 20 fg with a signal to noise ratio of greater than 10:1. The other compounds were within an order of magnitude of this. It is thus feasible, at least in principle, to quantify components from all four groups of plant growth regulators from the same tissue.