RESUMO
The developmental plasticity of plants according to changes in their growth conditions is mediated by signalingmolecules called hormones. The major classes of plant hormones are auxin, gibberellins, abscisic acid, andethylene. Among these, the most important is indole-3-acetic acid (IAA). Quantification of IAA in an extract ofapproximately 10 mg obtained from the cambial zone of Eucalyptus leaves was performed by ultra-performanceliquid chromatography coupled with electrospray ionization tandem mass spectrometry (UPLC/ESI-MS/MS). Theleaves were extracted using acetone, and the extract was analyzed using a reverse-phase column (Acquity UPLCBEH C18, 2.1 mm × 100 mm, 1.7 µm) at a flow rate of 0.2 mL/min with gradient elution of an aqueous mobile phase(containing 0.1% formic acid) with methanol. This gradient elution provided an excellent performance in terms ofspecificity/selectivity, linearity, precision, and ruggedness/stability. In addition, the run time was short (6 min), withexcellent linearity (R2 > 0.99) in the range of 10–70 ng/mL. The structure of IAA was elucidated using UPLC/ESIMS/MS, operating and quantifying in multiple reaction monitoring (MRM) mode.