Identification and quantitation of auxins in plants by liquid chromatography/electrospray ionization ion trap mass spectrometry

Auxin is an important phylohormone, which regulates specific physiological responses such as division, elongation and differentiation of cells. A new method using liquid chromatography/electrospray ionization ion trap mass spectrometry (LC/ESI-ITMS) has been developed for identification and quantitation of four auxins. Under the optimum conditions, four auxins (indole-3-acetic acid, indole-3-propionic acid, indole-3-butyric acid and 1-naphthylacetic acid) were completely separated and quantitated within 7 min with a minimum detection limit of 8.0 ng mL(-1) with relative standard deviations lower than 5.0%. This method also has been applied to analysis of auxins in Chinese cabbage where, even with a complicated serious background perturbation due to the natural biological matrix, the mean recoveries ranged from 77.5% to 99.8%. Finally, we discuss the MS-relevant properties of the identified auxins in detail.