Analysis and characterization of naphthalene and its alkyl derivatives in gasolines using gas chromatography/mass spectrometry

Abstract

At least 38 of the title compounds up to C15 polyalkylnaphthalenes are found in gasolines using a fused silica SE-54 capillary gas-chromatography column coupled to a quadruple mass spectrometer operating with electron ionization (EI) or methane chemical ionization (CI). Mass chromatograms are used to distinguish the alkylnaphthalenes from other coeluting aromatics. Retention indices relative to naphthalene and phenanthrene are given for at least 20 of the identified components, and semi-quantitation is given. The abundances, as percent within isomeric groups, are reported and compared to reports previously done on crude oils and coals tars. The abundances of the alkylnaphthalenes found are correlated with thermodynamic data from literature. The CI mass spectra show the expected abundant protonated molecules and reagent-gas adducts, but differences in minor-ion abundances reflect different tendencies of isomers or homologues to undergo hydride abstraction and skeletal fragmentation. These tendencies are rationalized according to degree of substitution and ionic stability, confirming the extending another CI report on some of these compounds.