The disclosure provides dyes for marking hydrocarbon compositions. More particularly, the disclosure relates to non-mutagenic dyes for marking hydrocarbon com positions.

The present invention relates to a process for preparation of metal free, nontoxic, hydrocarbon fuel compatible fluorescent carbon quantum dots (CQD), which act as marker as well as lubricity improver. CQDs are highly stable in non-polar hydrocarbons, at ppm level exhibit distinct fluorescent color upon irradiation with light of specific wavelength and exhibit distinct spectral properties compared to non-polar base hydrocarbons.

A method of marking a hydrocarbon liquid comprising adding to said hydrocarbon liquid a tracer compound, the tracer compound being a substituted biphenol ether having a core structure of Formula I, wherein the two R groups are the same or different and selected from straight chain, branched or cyclic alkyl groups, phenyl or substituted phenyl groups, benzyl or substituted benzyl groups, or the two R groups form a single substituent linked intramolecularly to both oxygen atoms, and wherein one or both of the aromatic rings of the core structure is further substituted with at least one non-planar group.

##STR00001##

A method for marking a petroleum hydrocarbon or a liquid biologically derived fuel; said method comprising adding to said petroleum hydrocarbon or liquid biologically derived fuel at least one compound that is a R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5, R.sup.6, R.sup.7 and R.sup.8—substituted dibenzofuran, wherein R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5, R.sup.6, R.sup.7 and R.sup.8 independently are hydrogen, hydrocarbyl, hydrocarbyloxy, aryl or aryloxy; provided that R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5, R.sup.6, R.sup.7 and R.sup.8 collectively have at least two carbon atoms; wherein each compound having formula (I) is present at a level from 0.01 ppm to 20 ppm.

A method for marking a petroleum hydrocarbon or a liquid biologically derived fuel; said method comprising adding to said petroleum hydrocarbon or liquid biologically derived fuel at least one compound that is a R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5, R.sup.6, R.sup.7, R.sup.8, R.sup.9 and R.sup.10-substituted xanthene, wherein R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5, R.sup.6, R.sup.7, R.sup.8, R.sup.9 and R.sup.10 independently are hydrogen, hydrocarbyl, hydrocarbyloxy, aryl or aryloxy; wherein each compound of formula (I) is present at a level from 0.01 ppm to 20 ppm.

The invention provides a composition which comprises an apolar medium and a tracer compound, which tracer compound comprises a hydrophobic group and an oligonucleotide. Various uses of the tracer compound are also described.

A composition is provided that includes a carbonaceous feed material to be combusted to generate an off-gas and an identifier. The identifier is associated with a predetermined composition, characteristic or property of the feed material or the off-gas.

A method for marking a petroleum hydrocarbon or a liquid biologically derived fuel; said method comprising adding to said petroleum hydrocarbon or liquid biologically derived fuel at least one compound that is a R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5, R.sup.6, R.sup.7 and R.sup.8—substituted dibenzofuran, wherein R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5, R.sup.6, R.sup.7 and R.sup.8 independently are hydrogen, hydrocarbyl, hydrocarbyloxy, aryl or aryloxy; provided that R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5, R.sup.6, R.sup.7 and R.sup.8 collectively have at least two carbon atoms; wherein each compound having formula (I) is present at a level from 0.01 ppm to 20 ppm.

The use, as markers of petroleum products, crude oils, biofuels or lubricants, of rare earth complexes or one of the constituents thereof chosen from rare earth ligands or salts, being capable of forming a rare earth complex after the addition of a developing solution. Preferably, the rare earth complex can be detected by time-resolved fluorescence. Also, a marking method and a method for detecting a rare earth complex as a marker of petroleum products, crude oils, biofuels or lubricants.

A composition is provided that includes a carbonaceous feed material to be combusted to generate an off-gas and an identifier. The identifier is associated with a predetermined composition, characteristic or property of the feed material or the off-gas.