Concentrates of petroleum triamantanes (heptacyclo[7,7,1,1(3,15),0(1,12),0(2,7),0(4,13),0(6,11)]octadecanes) have been obtained by thermal-diffusion separation, and triamantane and 9-methyltriamantane have been identified. It has been shown that foreign peaks present in the m/z 240 and m/z 239 mass chromatograms of the paraffin-cycloparaffin fractions of crude oils do not hinder the identification of triamantanes and calculation of their relative concentrations.