Three replications were conducted for each column in these experiments.
The carrier gas was nitrogen (N2) at a linear flow rate of 25 cm/s. The MS detector was operated at 194 C. The scan
range was from 35 to 450m/z at a scan rate of 0.50 scan/s. Solvent delay was 15 min. To check the purity of each GC peak, the mass spectra were obtained from samples corresponding to various parts of each peak. Normal saturated hydrocarbons (C7–C30), cyclohexane, cyclopentane, fatty acids, alcohol, benzene derivatives, and other compounds were putatively identi-fied by mass-spectral database search (National Institute of Standards and Technology (NIST)/Environmental Protection Agency/National Institutes of Health databases), followed by matching with the spectra of the MS library. All volatile compounds showing mass spectra with match factors P90% were included in a ‘‘positive list’’ of tentatively identified compounds. Fourier-transform infrared spectroscopy (FT-IR) was used to investigate and predict any physiochemical inter-actions between the different compounds in a formulation. The spectra obtained from these samples were compared and interpreted with reference to the significance of the shifts in the peaks of the functional groups.