Matrix-assisted laser desorption/ionization mass spectrometry for the analysis of polyamines in plant micro-tissues using cucurbituril as a host molecule

In this study, a matrix-assisted laser desorption/ionization (MALDI) mass spectrometry (MS) strategy using cucurbit[ n ]uril (CB[ n ]) as a host molecule is proposed for the analysis of low molecular weight (LMW) compounds in complex samples. As a proof-of-concept, CB[6] was selected as the host molecule, and endogenous polyamines in plant tissue were chosen as the target analytes. Due to the molecular recognition and mass shifting properties of CB[6], the ionic signals associated with polyamines were moved to the higher mass region (>1000 Da) after specifically binding to CB[6], while signal interference derived from the conventional organic matrix and the complex sample matrix remained in the low mass region because of the incompatibility of their molecular size with CB[6] cavities. The strategy not only facilitated the analysis of LMW compounds in complex samples by MALDI MS, but also offered high throughput by accomplishing the entire analytical procedure within 10 min. The detection of polyamine concentration showed good linearity in the range of 0.02–10.0 ng/μL with correlation coefficients (R) greater than 0.9915. The limits of detection were 8.8–28.8 pg. The good reproducibility and reliability of the method were demonstrated by excellent intraday and interday precisions with relative standard deviations less than 7.9%, and the recovery ranged from 92.1% to 117.1%. Finally, the good sensitivity of the method allowed for the quantitative analysis of endogenous polyamine concentrations in various micro-tissues of Arabidopsis thaliana (20.0–740.0 μg fresh weight for each sample).