Elimination of Preliminary Depentanization of Gasoline Prior to Hydrocarbon-Type Analysis by Mass Spectrometry

Abstract

The usual mass spectrometric procedure for the determination of hydrocarbon types in nonolefinic gasolines containing Cg and lighter hydrocarbons is encumbered by a preliminary distillation to remove the C5 and lighter hydrocarbons. Now, however, the need for preliminary depentanization can be eliminated by the use of gas chromatography in conjunction with the mass spectrometric analysis. Cg and lighter hydrocarbons are determined by any gas chromatographic method which expresses results in liquid volume per cent. On the basis of these data, the mass spectrum of the total gasoline is mathematically corrected for the presence of Cg and lighter hydrocarbons. No loss of accuracy is experienced, and costly distillation time, 2 to 4 hours, is eliminated.

Resolution of cyclopentanes and cyclohexanes in gasolines by mass spectrometry

“…Francis (3) and Hastings el al. (5) have made use of the cyclopentyi-and cyclohexylmethylene absorption in the infrared to determine relative concentrations of Cb and Cg ring hy-drogens present in high molecular weight fractions. No information on the number of rings is available from this method.…”

Mass Spectrometry

“…Gasoline is analyzed for olefins (335), for isoparaffins and n-paraffins in olefinfree material (135), and without prelimi-nary depentanization (232). Analyses of medium-viscosity lubricating oils (4) and heavy oils (229) are reported.…”