Samples (digested) were analyzed by gas chromatography/mass spectrometry (GC/MS), using Agilent-Technologies (Little Falls, CA, USA) 6890N Network GC system, equipped with an Agilent-Technologies 5975 inert XL Mass selective detector and Agilent- Technologies 7683B series auto injector. The separation was performed on Agilent Technologies capillary column HP5MS (30 m × 0.25 mm; film thickness 0.25 μm). Sample volume of 1.0 μL was injected into the column with split ratio 100:1. The carrier gas used was Helium at a flow rate of 1.2 mL min-1. The column temperature was programmed from 150oC to 250 oC at a linear ramp rate of 4 oC min-1, while the initial and final hold up time was 1 and 5 min, respectively. An electron ionization mode, with ionization energy of 70 eV, was used for GC/MS detection. Injector and MS transfer line temperature were set at 250 oC and 260 oC, respectively. The scanning mass range was selected from 30-550 m/z (mass-to-charge ratio). The unknown samples were identified on the basis of matching of their relative retention times with those of standards (Sigma Chemical Co., St Louis, MO, USA). Samples were further identified and authenticated using their MS spectra compared to those from the NIST mass spectral library of the GC/MS system.