Mass Fragmentation Studies of α-tomatine and Validation of a Liquid Chromatography LTQ-Orbitrap Mass Spectrometry Method for its quantification in Tomatoes.

Tomatoes, members of the Solanaceae plant family, produce biologically active secondary metabolites, including glycoalkaloids, which may have both adverse and beneficial biological effects. By using the linear ion trap (LIT) mass spectrometry, multistage collision-induced dissociation (CID) experiments (MSn) were performed to elucidate characteristic fragmentation pathways of the glycoalkaloid α-tomatine. High-resolution with high-accuracy mass analysis using an Orbitrap Fourier transform MS (FTMS) with higher-energy CID (HCD) was used to produce mass spectra data across a wide spectral range for confirmation of proposed ion structures and formulae. In addition, a new liquid chromatography method that utilized LTQ Orbitrap MS was developed for the analysis of α-tomatine in tomatoes. Recoveries of α-tomatine were >96.0 % with relative standard deviations (RSD) below 7.98 %. The limit of detection (LOD) was 0.002 mg/kg. The limit of quantitation (LOQ)was 0.005 mg/kg. The linear range was between 0.010 and 10 mg/kg with an excellent correlation coefficient (R2)≥0.9991. Various tomato samples were analyzed for method application, and the level of α-tomatine in the 11 samples analyzed ranged from 0.0011to 0.3077 mg/kg.