An Improved Method of UPLC-PDA-MS/MS Analysis of Lycopene Isomers

Abstract

The aim of the study was to develop a rapid method for analysis of lycopene extracted from tomato puree using UPLC. Further, conditions were optimized to obtain characteristic ions to distinguish lycopene isomers by using APCI-MSMS mode. Chromatographic separation of (all-E)-lycopene and (Z)-lycopene isomers were separated by reversed-phase CSH Phenyl-Hexyl column with short run time and good resolution. Radical cation [M]+ of (all-E)-lycopene and major (Z)-lycopene isomers upon collision-induced dissociation (CID) produced a number of characteristic ions; (13Z)- and (15Z)-lycopene isomers were characterized by the loss of 15 Da (CH3) to form ions of m/z 521, from the molecular ion m/z 536. In addition, fragmentation patterns of (all-E)-/(Z)-lycopene were also compared with (all-E)-β-carotene with similar molecular mass. Selective CID coupled with UV-Visible spectra was used to differentiate the geometrical isomers of lycopene. The assessment could be helpful in the analysis of carotenoid isomers.