Multiclass Determination of Phenolic Compounds in Different Varieties of Tomato and Lettuce by Ultra High Performance Liquid Chromatography Coupled to Tandem Mass Spectrometry

Tomato and lettuce are main components of the Mediterranean Diet and it is important to know their content in phenolic compounds, considering they have beneficial effects on human health. In this work, more than 25 phenolic compounds were simultaneously analyzed by ultra-high performance liquid chromatography coupled to triple quadrupole tandem mass spectrometry, including phenolic acids, flavonols, and flavones. Several varieties of lettuce and tomato were evaluated and total phenolic content ranged from 68 to 212 mg/kg dry weight for lettuce, and from 341 to 1296 mg/kg dry weight for tomato, being the chlorogenic acid the compound detected at the highest concentration in both types of vegetables (lettuce from 9 to 126 mg/kg dry weight, tomato from 96 to 538 mg/kg dry weight), although in tomato the content of quercetin-3-O-rutinoside (from 29 to 460 mg/kg dry weight) was also important. On the other hand, the minor compounds detected were quercetin-3-O-derivate (up to 1 mg/kg dry weight) in tomato, and apigenin O derivate, luteolin C glucoside, and isorhamnetin 3-O-glucoside in lettuce. It was observed that the total phenolic content in the plum cherry tomato was significantly higher than in the other varieties, whereas in lettuce, the differences were not statistically different.