A new derivatization approach for the rapid and sensitive analysis of brassinosteroids by using ultra high performance liquid chromatography-electrospray ionization triple quadrupole mass spectrometry

In this work, a new labeling reagent, 2-bromopyridine-5-boronic acid (BPBA), was introduced to derivatize brassinosteroids (BRs). The BPBA not only provided a very simple and rapid labeling procedure, but also remarkably increased the detection sensitivity of BRs. Based on this new labeling reaction, a rapid and sensitive method for BRs' analysis in Arabidopsis thaliana was established by using the ultra high performance liquid chromatography-electrospray ionization triple quadrupole mass spectrometry (UHPLC-ESI-QqQ-MS). The extraction and purification procedure of the plant sample was also simplified and improved in this work. Good linearities were obtained for three BRs with the determination coefficients (R-2) about 0.9999. The limits of detection (S/N=3) for three BRs were found to be 2.00-8.00 ng/L while the limits of quantification (S/N=10) were 6.00-23.0 ng/L The RSD % for all three samples are lower than 8.67% (n=5). The recoveries of three BRs spiked in A. thaliana samples were from 76.9% to 86.1%. Using this method, the endogenous 0.055 ng/g fresh weight (FW) 24-epiBR and 0.070 ng/g (RN) 28-epihomoBR were successfully detected from only 2 g A. thaliana plants. (C) 2012 Elsevier B.V. All rights reserved.