Highly sensitive high-throughput profiling of six phytohormones using MS-probe modification and liquid chromatography-tandem mass spectrometry.

We describe a method for highly sensitive high-throughput analysis of six major phytohormones; cytokinins (23 species), auxins (7 species), abscisic acid (ABA), gibberellins (GAs, 11 species), salicylic acid (SA), and jasmonic acid (JA). The method consists of solid-phase extraction using 96-well column plates and liquid chromatography coupled with a tandem quadrupole mass spectrometer. In order to improve the quantification limit of negatively charged compounds and especially GAs, we use a chemical modification with an "MS-probe" that contains a quaternary amine moiety. The method requires plant tissue of <100 mg fresh weight for quantification and enables us to analyze large number of plant samples at a time.