Comparative study of Colombian citrus oils by high-resolution gas chromatography and gas chromatography-mass spectrometry

Essential oils from fruit peel and leaves of colombian lemon ( Citrus volkameriana ), mandarin ( C. reticulata ) and orange ( C. sinensis ) were obtained by steam distillation and/or cold pressing. The extracts were analysed by high-resolution gas chromatography using either a flame ionization detector or a mass selective detector (electron impact ionization, 70 eV). The oil constituents were identified according to their mass spectra and Kova´ts retention indices determined on both polar and non-polar stationary phase capillary columns. The concentration of volatile secondary metabolites was maximum when the citrus fruits were at an intermediate maturation stage characterized by a greenish yellow coloration (45–75% green). While citrus peel oils contained from 94.01 to 98.66% of monoterpenes (C 10 H 16 ), limonene as a major component and from 0.82 to 5.84% of oxygenated compounds, the extracts from citrus leaves contained only 65.26, 31.23 and 79.43% of monoterpenes (C 10 H 16 ) in lemon, mandarin and orange, respectively. Oxygenated compounds in these oils represented 33.08, 68.47 and 16.38%, respectively.