2.3. Analysis Using GC-MS/MS

Analysis was performed by an Agilent 7890B gas chromatograph, equipped with a 7010 mass selective detector triple quadrupole mass spectrometer system (Palo Alto, CA, USA). Chromatographic separation was achieved using a DB-5MS UI (5% diphenyl-95% dimethyl siloxane phase, 30 m × 0.25 mm I. D; 0.25 µm film thickness) from a J&W Scientific (Santa Clara, CA, USA) capillary column. The temperature of injector was 300°C. One microliter of each extract was injected in the split mode (2  :  1). Helium as carrier gas (99.999%) flow was 1 mL/min. The GC oven temperature program was as follows. The initial temperature of 150°C was held for 3 min after injection before it was increased up to 300°C at 10°C/min held for 12 min. Nitrogen (99.999%) was used as collision gas. The running time was 30 min, divided into seven segments of time for each selected product ion to increase sensitivity and selectivity. The transfer line and ion source temperature were set at 250 and 230°C, respectively. The mass spectrometer is tuned on electron impact ionization (EI) at 70 eV in the multiple reaction monitoring (MRM) mode.