A method for determining authenticity of a petroleum hydrocarbon, wherein the petroleum hydrocarbon allegedly comprises at least one chemical marker, wherein said at least one chemical marker is selected from: i) a compound of general formula wherein the residues R 1 - R 12 are independently of each other selected from the group consisting of hydrogen, C 1 -C 4 -alkyl, the residues R a - R e, R a' - R e', R a" - R e" and R a′′′ - R e′′′ are independently of each other selected from the group consisting of hydrogen and C 1 -C 4 -alkyl, with the proviso that at least two of the residues R 1 - R 12 are selected from: ii) a compound of general formula wherein the residue -L- represents -CR 13 =CR 14 -; the residues R 13 and R 14 are independently of each other selected from the group consisting of hydrogen and methyl; the residues R 15 - R 24 are independently of each other selected from the group consisting of hydrogen and C 1 -C 4 alkyl; and n is an integer comprised between 2 and 6; iii) an aromatic compound substituted by one or more N,N-disubstituted amino groups, wherein the substituents of the one or more N,N-disubstituted amino groups are independently of each other selected from C 1 -C 6 -alkyl or the two substituents of a N,N-disubstituted amino group taken together form a residue -(CH 2) p -, wherein p is an integer comprised between 2 and 6; and iv) an aromatic compound substituted by at least one group selected from C 1 -C 4 -alkyloxy; wherein the method comprises the following steps: a-1) acquiring a sample of the petroleum hydrocarbon; b-1) vaporizing said sample to provide a gaseous sample; c-1) illuminating the gaseous sample with a pulsed laser light of a predetermined wavelength of between about 300 nm and about 370 nm, thereby producing gaseous ions; and d-1) analyzing the gaseous ions obtained at step c-1) by ion mobility spectrometry or mass spectrometry to detect a presence or an absence of said at least one chemical marker in the petroleum hydrocarbon, and thereby determining the authenticity of said petroleum hydrocarbon. i) a compound of general formula wherein the residues R 1 - R 12 are independently of each other selected from the group consisting of hydrogen, C 1 -C 4 -alkyl, the residues R a - R e, R a' - R e', R a" - R e" and R a′′′ - R e′′′ are independently of each other selected from the group consisting of hydrogen and C 1 -C 4 -alkyl, with the proviso that at least two of the residues R 1 - R 12 are selected from: the residues R 1 - R 12 are independently of each other selected from the group consisting of hydrogen, C 1 -C 4 -alkyl, the residues R a - R e, R a' - R e', R a" - R e" and R a′′′ - R e′′′ are independently of each other selected from the group consisting of hydrogen and C 1 -C 4 -alkyl, with the proviso that at least two of the residues R 1 - R 12 are selected from: ii) a compound of general formula wherein the residue -L- represents -CR 13 =CR 14 -; the residues R 13 and R 14 are independently of each other selected from the group consisting of hydrogen and methyl; the residues R 15 - R 24 are independently of each other selected from the group consisting of hydrogen and C 1 -C 4 alkyl; and n is an integer comprised between 2 and 6; the residue -L- represents -CR 13 =CR 14 -; the residues R 13 and R 14 are independently of each other selected from the group consisting of hydrogen and methyl; the residues R 15 - R 24 are independently of each other selected from the group consisting of hydrogen and C 1 -C 4 alkyl; and n is an integer comprised between 2 and 6; iii) an aromatic compound substituted by one or more N,N-disubstituted amino groups, wherein the substituents of the one or more N,N-disubstituted amino groups are independently of each other selected from C 1 -C 6 -alkyl or the two substituents of a N,N-disubstituted amino group taken together form a residue -(CH 2) p -, wherein p is an integer comprised between 2 and 6; and iv) an aromatic compound substituted by at least one group selected from C 1 -C 4 -alkyloxy; wherein the method comprises the following steps: a-1) acquiring a sample of the petroleum hydrocarbon; b-1) vaporizing said sample to provide a gaseous sample; c-1) illuminating the gaseous sample with a pulsed laser light of a predetermined wavelength of between about 300 nm and about 370 nm, thereby producing gaseous ions; and d-1) analyzing the gaseous ions obtained at step c-1) by ion mobility spectrometry or mass spectrometry to detect a presence or an absence of said at least one chemical marker in the petroleum hydrocarbon, and thereby determining the authenticity of said petroleum hydrocarbon. a-1) acquiring a sample of the petroleum hydrocarbon; b-1) vaporizing said sample to provide a gaseous sample; c-1) illuminating the gaseous sample with a pulsed laser light of a predetermined wavelength of between about 300 nm and about 370 nm, thereby producing gaseous ions; and d-1) analyzing the gaseous ions obtained at step c-1) by ion mobility spectrometry or mass spectrometry to detect a presence or an absence of said at least one chemical marker in the petroleum hydrocarbon, and thereby determining the authenticity of said petroleum hydrocarbon.