The Essential Oil of Pistacia vera L. at Various Temperatures of Direct Thermal Desorption Using Comprehensive Gas Chromatography Coupled with Time-of-Flight Mass Spectrometry

The essential oil obtained from the hulls of Pistacia vera fruits using direct thermal desorption was resolved using comprehensive gas chromatography (GC×GC) coupled with time-of-flight mass spectrometry (TOF-MS). A range of temperatures (100, 150, 200, 250 °C) for thermal desorption were applied to extract volatile organic compounds from around 10mg of raw sample. Although different species profiles were produced at each temperature (notably browning products above 200 °C), -pinene and (Z)--terpineol were found to be the major components at all temperatures studied. The number of compounds observed increased with increasing temperature. A temperature of 150 °C is recommended as optimum for the direct thermal desorption of volatiles from matrices such as fruit hulls. The GC×GC separation chromatographically resolved several hundred components which when coupled for detection with TOF-MS gave high probability identifications for around 100 compounds. The comprehensive separation also separated a number of components which remained unresolved on a single GC column, such as camphene with butyrolactone and dodecane with p-cymene.