Determination of Petitgrain oils landmark parameters by using Gas Chromatography-Combustion-Isotope Ratio Mass Spectrometer and Enantioselective Multidimentional Gas Chromatography

Petitgrain oils are extracted by steam distillation from leaves, small branches and buds of different Citrus plants species. These products are extremely important in perfumery thanks to their odour properties. The quality of petitgrain oils is compromised by the dubious origin of the raw material available for the distillation and by the common practice to blend with sweet orange petitgrain, available at low price, the more valuable ones. The present work aims to analyze genuine Italian petitgrain oils by using gas chromatographycombustion- isotope mass spectrometry (GC-C-IRMS) to determine the terpenic signature of eight components (-pinene, -pinene, -terpineol, neral, geranial, neryl acetate, geranyl acetate and -caryophyllene) in lemon petitgrain oils and five (-thujene, -pinene, -pinene, myrcene and methyl N-methylanthranilate) in mandarin petitgrain oils. The results are compared with the authenticity ranges previously determined by the same analytical approach, analyzing numerous samples of the corresponding Citrus species of Italian cold-pressed peel oils, produced in the same geographic region. An internal isotope standard (i-std) is introduced to evaluate only the petitgrains secondary biogenetic pathway and to compare the carbon isotope fractionation occurring during the mevalonate biosynthesis in Citrus petitgrains and in peel oils. In addition, petitgrains oils are characterized analyzing the composition of the whole oil and the enantiomeric distribution of selected chiral compounds by using gas chromatography (GC-FID) and by multidimensional and conventional enantioselective gas chromatography (MDEs-GC and Es-GC).