A frequent problem in quantitative gas-chromatographic analyses of multicomponent hydrocarbon mixtures results from the fact that certain hydrocarbons might not be available as gas-chromatographic standards, As a consequence assumptions have to be made about their correction factors, which account for the dependency of detector signals on molecular structures. These estimates often lead to major analytical errors. For that reason a group contribution method has been developed by which correction factors for hydrocarbons with paraffinic, naphthenic and aromatic molecular structures can be calculated from increment values of 17 structural groups.