Esquire hct ion

An Esquire HCT ion trap mass spectrometer (Brüker) was used in electrospray + mode. Mass spectrometer conditions were optimized independently for oxidized MGDGs (arabidopsides A and B), oxidized DGDG (arabidopside D) and oxidized acyl-MGDG (arabidopsides E and G). The capillary voltage was set at − 4500 V, endplate offset at − 500 V, nebulizer pressure at 50 psi and the flow rate of the dry gas at 10 L min^-1. Mass spectrometer optimized parameters that differed for the analysis of each arabidopside class are presented in Supplemental Table 1. The mass resolution was calculated for each arabidopside as the ration between the mass of the quantification ion and the width of that peak at 50% peak height. Mass resolutions were, respectively, of 1,585 for arabidopside A, 2,051 for arabidopside B, 1,975 for arabidopside D, 2,143 for arabidopside E and 2,199 for arabidopside G. Data treatment was performed using Brüker Daltonics esquire DataAnalysis software.