Identification of nonvolatile components in lemon peel by high-performance liquid chromatography with confirmation by mass spectrometry and diode-array detection

High-performance liquid chromatography (HPLC) with diode-array detection and thermospray mass spectrometry (LC-TSP-MS) were used to identify nonvolatile compounds in a lemon peel extract. In this way, the retention time characteristics, the UV-Vis spectra and the mass spectra provide structural information without the necessity of isolating the individual compounds. The lemon peel extract was separated into petroleum ether, chloroform, ethyl acetate and butanol fractions. The chloroform fraction was found to contain mainly the limonoids; the petroleum ether fraction contained coumarins, phenyl propanoid glycosides and flavones-C-glucosides; and the ethyl acetate fraction which had the best antioxidant activity, was found to contain flavonols, flavones-O-glycosides and flavonones.