This method describes a procedure for determining paraffin, olefin, naphthene and aromatic hydrocarbon types in stabilized gasolines or fractions therefrom. The endpoint of these stocks (ASTM D 86) should not exceed 196°C (385°F), see NOTE 1. Paraffins and naphthenes are determined by carbon number with cyclopentane, methylcyclopentane and cyclohexane determined individually. C₆ minus hydrocarbons can be reported either individually or by carbon number. Aromatics are determined by carbon number through C₈ with the C₉+ determined as a composite. Olefins are reported undistributed.