Quantitative analysis of 1-aminocyclopropane-1-carboxylic acid by liquid chromatography coupled to electrospray tandem mass spectrometry

Liquid chromatography coupled to electrospray tandem mass spectrometry was investigated as a method for the analysis of 1-aminocyclopropane-1-carboxylic acid (ACC) in plant tissues. Isotopically labelled ACC ([H-2(4)]ACC) was used as an internal standard. After solid-phase extraction, samples were derivatized with phenyl isothiocyanate and the obtained phenylthiohydantoin compound was analyzed by multiple reaction monitoring of the appropriate [MH](+) to product ion transitions (219-->98 and 223-->102). Optimal conditions for positive ion electrospray tandem mass spectrometry showed a linear response within a concentration range of 0.1-100 pmol per 10 mu l injected and between cold and deuterated ACC within a range of 1:50 to 50:1. A detection limit was observed of 0.1 pmol injected on column. The high specificity of detection allows the analysis of endogenous ACC levels in plant extracts without excessive purification. Despite the complex nature of the plant matrices, chromatographic conditions were developed under which a complete baseline separation with interfering compounds was obtained within an analysis time of 12 min. (C) 1997 Elsevier Science B.V.