This method is for organic analysis of distillate or petroleum fractions boiling in the range of 36 – 435°C using comprehensive two-dimensional gas chromatography (GCxGC) coupled with a flame ionization detector (FID). Results, expressed in mass-% can be reported in three different formats: 1) molecular types indexed to n-alkanes; 2) molecular type homologous series by carbon number and 3) user specified resolved compounds or molecular type groups. Individual compounds and molecular type groups are identified by their location, as plotted on a chromatographic two-dimensional image. Olefins, unless specifically identified, are lumped with other molecular types, typically cycloparaffins. Heteroatomic species, when resolved, can be determined; otherwise they are lumped with other aromatic hydrocarbons. The lower limit of detection for a single molecular component is typically below 0.004 mass-% with the specified equipment. .