RAPID HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHIC METHOD FOR THE QUANTIFICATION OF ALPHA-TOMATINE IN TOMATO

A method for the determination of the glycoalkaloid alpha-tomatine in tomatoes and tomato plant material is described. The alpha-tomatine is extracted with methanol and subsequently prepared for analysis using a C-18 cartridge column. The alpha-tomatine was applied on the cartridge in 40% methanol and eluted with 80% methanol. A Nucleosil 5-NH2 column was employed for the high-performance liquid chromatography (HPLC) with acetonitrile-20 mM potassium dihydrogen phosphate (75:25, v/v, pH 6.1) as the mobile phase. Recoveries of spiked alpha-tomatine ranged from 91% to 98% for different amounts spiked. The calibration graph was linear in the range 5-250 mu g/mL for alpha-tomatine. Survey data are presented for tomatoes and tomato plant material collected from commercial growers and from the Dutch auctions.