Initially, GCMS parameters were optimized by using direct liquid injection of EO. The individual components found in EO were separated on Rtx-5Sil MS column. The n-alkane standard (C-7 to C-35) was injected for determination of LRIs of the components. The FFNSC library with LRIs was used for qualitative confirmation. The headspace parameters for the EO in presence of complex matrix like diluent, broth and culture were optimized.
The concentration of EO showing moderate antibacterial activity was selected for HS studies. The tube (A) ‘Positive control’, containing broth inoculated with culture, shows bacterial growth. The tube (B) ‘Negative control’, containing EO in broth and tube (C) ‘Test’, containing EO in broth, inoculated with culture, did not show any bacterial growth. Tube (C) in spite of being inoculated with bacterial culture; the growth was inhibited due to the presence of EO.
The chromatogram obtained by HS-GCMS analysis of tube (C) after 18 hours of incubation at 37°C was compared with its zero hour chromatogram. Some of the components of EO show appreciable decrease in area after 18 hours incubation.
Hence, the decrease in the area of some of the components could be attributed to their antibacterial activity against selected culture.