The determination of lycopene Z-isomer absorption coefficient on C30-HPLC

Both E- and Z-isomers of lycopene are encountered in nature. Although they were separated on C30-HPLC by the mobile phase consisting of CH₃CN-MeOH (A) and MTBE (B), the quantification of Z-isomers cannot be archived at present because either their commercially available reference samples are currently lacking, or they are unstable. In this study, both the specific and molar absorption coefficients of 5, 9, and 13 Z-isomers in the mobile phase were determined on the analytical C30-HPLC-PDA-ELSD, and further verified on the preparative C30-HPLC-PDA. The specific and molar absorption coefficients of 5, 9, and 13 Z-isomers were finally verified to be $$  = 3,422 and ε _mol = 183,717, $$  = 2,183 and ε _mol = 117,199, and $$  = 1,119 and ε _mol = 60,076, respectively, in the mobile phase. With these determined coefficients, the quantifications of 5, 9, and 13 Z-isomers were able to be archived on C30-HPLC-PDA with the mobile phase applied in this investigation.