Gas Chromatographic Analyses of Complex Hydrocarbon Mixtures Void of n-Paraffin Retention Index Markers Using Joint Mass Spectral and Retention Index Libraries

Complex hydrocarbon mixtures are analyzed by a gas chromatographic/mass spectrometric (GC/MS) method. Information from both a mass spectral library and a relative retention index library is used to identify the constituents of the mixtures. The ability of the mass spectral library to solve ambiguous retention index identifications and the ability of the retention index library to choose proper identifications from a ranking of mass spectral identifications is shown. A unique computer algorithm that allows the use of a Kovats retention index system on samples that do not contain a contiguous spectrum of the n-paraffins is demonstrated.