Determination of tomatine in foods by liquid chromatography after derivatization

A liquid chromatographic method for measuring tomatine levels in tomatoes and tomato products was developed. Tomatine was extracted with 1% acetic acid and purified on a C18 cartridge. Tomatine in the eluate was acetylated with acetic anhydride and isolated on a C18 cartridge. The solvent in the eluate was evaporated and the residue was dissolved in acetonitrile. An aliquot was injected into an Inertsil ODS-2 HPLC column and the acetylated tomatine was measured at 205 nm using a UV detector. The limit of determination was 1 microgram g-1. Tomatine was detected in the green portions of tomatoes and in tomato ketchups and juices at levels below 7 micrograms g-1.