Canadian General Standards Board

Methods of Testing Petroleum and Associated Products Standard Test Method for the Identification of Hydrocarbon Components in Automotive Gasoline Using Gas Chromatography
 N CAN/CGSB-3.0 NO. 14.3-99

Annotation

This test method is a standard procedure for the determination of paraffins, olefins, naphthenes, aromatics and unknowns (P.O.N.A.U.) in automotive gasolines using gas chromatography.

The final boiling pint of samples should not exceed that of nC15.

Individual hydrocarbon components or groups of coeluting components greater than or equal to 0.01% by mass are determined.

The separation of individual hydrocarbons by the procedure described in this test method is not absolute and will result in some peaks that represent coeluting compounds (Table 1).

A limitation of the method is that toluene and 2,3,3-trimethylpentane may coelute. If isooctane (2,2,4-trimethylpentane) and 2.3,4-trimethylpentane present in the gasoline sample, it is probable that the sample contains 2,3,3-trimethylpentane. The concentration of 2,3,3-trimethylpentane is almost certain to be less than the concentration of 2,3,4- trimethylpentane. When determining the concentration of toluene and 2,3,3- trimethylpentane, it is essential that the gas chromatographic integrator has individual peak processing capabilities including peak expansion and perpendicular drop. To detect 2,3,3-trimethylpentane and toluene, these compounds must be within a 5:l ratio of each other with either compound having the greater concentration. If these components are present in a greater than 5:l ratio, the toluene and 2,3,3-trimethylpentane may appear as a coeluted peak, thus causing the component in the smallest concentration to be integrated with the more concentrated component.