On Identification of C11–C13 Adamantanes in Crude Oils

The paper demonstrates that mass chromatograms with the characteristic ions (m/z 135, 149, and 163) of C11–C13 petroleum alkyladamantanes contain C10–C12 monoaromatics in addition to protoadamantanes. The monoaromatic hydrocarbons were isolated from a 150–250°C fraction of marine oil by preparative high-performance liquid chromatography with a refractometric detector, then analyzed by chromatography-mass spectrometry. The characteristic ions of mono-, di-, and trialkyl-substituted adamantanes (m/z 135, 149 and 163) were found to be also isotopes of molecular ions of C10, C11, and C12 monoaromatics with molecular weights of 134, 148, and 162, respectively. Thus, crude oils have significantly lower resources of protoadamantane hydrocarbons than previously thought.