Gas phase chromatography is carried out using a sophisticated device that enables the identification of the aromatic molecules present in an essential oil (up to 450 aromatic molecules). The graph provided by the chromatograph includes a series of peaks. Each peak represents a very specific aromatic molecule that is identified by software.
The aromatogram is an in vitro method of measuring the antibacterial power of essential oils. The technique is identical to that used to measure the bactericide activity of antibiotics.
Several series of discs impregnated with different essential oils are placed on microbial colonies. After a latency time at 37.5°, it is possible to measure in millimeters the diameter of the inhibition halo surrounding the discs.