This method combines the Senses of trained panellists as well as the technology gas chromatography to establish the correlation between specific chemicals and the odour concentration. Since the sample gas is passed through an olfactometer to be ‘sniffed’ from the panellist, it is also being analysed to identify the chemical compounds present. After the panellist senses an odour, she/he signs as the concentrations of chemicals present are compared. Gas-chromatography-Olfactometry GC-O is a procedure to combine the data supplied by compound characterization and from odour perception. GC-O utilises a GC-MS system equipped with an olfactory detection interface: in the outlet of the GC there is a sniffer mask, where a trained panellist can smell the gasoline and supply information regarding the existence of odour in it. At the close of the GC column, after separation of the chemical compounds in the gas mixture, the sample is split and an equal flux of it reaches the MS detector and the panellist.

The Panellist sniffs the gasoline, and whenever they sniff an odorous material, they give a sensorial response, concerning existence and type of odour. Every time the panellist perceives an odour, they push a button and explain the odour. In this manner, an fractogram is obtained, which allows to correlate the chemical information given by the chromatogram and the sensorial perceptions of panellist. GC-O consists in the combination of instrumental capacities and human nose and provides both sensorial and chemical information. 1 drawback of GC-O is that it is affected by subjectivity and inattention of the panellist. Indeed, panellist Distraction can provoke significant errors, particularly when odorous stimulus Is weak or short.

Special methodologies are sometimes needed. Reversed-phase chromatography is an elution process used in liquid chromatography analysis, using a mobile phase that is significantly more polar than the static phase. If the chemistry inside a given Column is inadequate to separate some analytes, two-dimensional chromatography may be used, which makes it feasible to direct a set of unresolved peaks onto another column with various properties. This procedure allows for the separation of substances that are indistinguishable from one another when using one-dimensional gas chromatography procedures. Additional specialized analysis Techniques include mimicked moving-bed chromatography, pyrolysis gas chromatography, fast protein liquid, counter current and chiral.