Analysis of calystegines in tomato-based products by liquid chromatography-Orbitrap mass spectrometry

Taking into account the high consumption of tomato and tomato-based products, a study of the occurrence of 7 nortropane alkaloids (calystegines A3, A5, B1, B2, B3, B4 and C1) in this type of matrix has been performed. For that purpose, a simple and fast solid-liquid extraction with methanol/water (50/50, v/v) has been developed, and then liquid chromatography, using a HILIC-A as stationary phase, coupled to high resolution mass spectrometry (LC-HRMS-Orbitrap) has been used for their determination. The developed method was validated and recoveries ranged from 96 to 121%, and relative standard deviations lower than or equal to 16% were obtained. Limits of quantification (LOQ) were established at 0.1 (B4), 0.25 (B3) and 0.5 (A3, A5, B1, B2 and C1) mg/kg. Twelve different samples were analyzed, comprising 4 crushed tomatoes, 4 fried tomatoes and 4 jam tomatoes. Calystegines A3 and B2 were identified in all the analyzed samples, while calystegine B3 was determined in all the fried tomatoes as well as in two crushed tomatoes and one jam tomato at concentrations ranging from 0.4 mg/kg (calystegine B2) to 19.0 mg/kg (calystegine A3). Although calystegine A5 was also detected in all the samples, only 3 of them gave concentrations higher than LOQ. Additionally, calystegine B1 was found in one jam tomato at 1.9 mg/kg. (C) 2018 Elsevier B.V. All rights reserved.