A method for determination of tomatine in tomatoes and tomato products was developed using LC-MS/MS. Tomatine was extracted from these samples with 20% methanol aqueous solution containing 1% acetic acid. Cleanup was performed on sample solutions using a polymer-based OASIS HLB cartridge column. LC separations were performed using an Inertsil ODS-3 column and a linear gradient elution using 0.1% formic acid aqueous solution and 0.1% formic acid in acetonitrile as the mobile phase. Detection of MS was performed in positive ion electrospray ionization mode. The range of average recoveries of tomatine from 4 fresh tomatoes and 7 processed tomato products added with 0.01 mg/100 g were 80.3-94.8% and 76.8-95.5%, respectively. The limit of quantitation was estimated to be 0.01 mg/100 g, considering the limit of bitter stimulus. Using the present method, results of tomatine content in two tomatoes tasted bitter by consumers, were 1.04 mg/100 g and 1.54 mg/100 g. Further, results of a field survey of tomatine content in commercially available fresh tomatoes and processed tomato products were in the range of 0.01 mg/100 g to 3.05 mg/100 g. In addition, when tomatine was added to tomato and then heat-treated, no significant change of tomatine amount was observed by heating.
