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 labelled methane, such as LNG, has methane and a tracer, in the form of a slush of liquids and solids. The invention especially relates to LNG having a tracer. The labelled methane may comprise, in addition to the tracer, an odorant, and a carrier for the odorant. The odorant is ethyl acetate and/or ethyl mercaptan. The carrier for the odorant is propane, n-butane, iso-butane, or a mixture of two or more thereof. A process for preparing the liquid or slush involves liquefying a gas comprising methane and tracer.

The present invention relates to markers for liquids that can be used to authenticate the origin and genuineness of a liquid, preferably a bulk liquid such as fuel. For this purpose, the present invention teaches the use of a polymer capable of forming a semiconducting polymer particle (pdot) in the liquid in small amounts. The invention encompasses a liquid comprising a) a polymer that is capable of forming a semiconducting polymer particle (pdot), the concentration of the polymer being 10 ppm by weight or less, and b) an organic substance in an amount of 90% by weight or more. The invention furthermore envisages the use of such a polymer as an authenticating marker in a liquid, preferably a fuel, and a method for authenticating the genuineness and/or origin of a liquid comprising a polymer capable of forming a semiconducting polymer particle (pdot), comprising the steps i. concentrating, isolating and/or extracting the polymer capable of forming a semiconducting polymer particle (pdot); ii. aggregating the polymer or the polymer obtained in Step i. to form semiconducting polymer dots (pdots); iii. irradiating the formed pdots with electromagnetic radiation capable of exciting the pdots to emit electromagnetic radiation by fluorescence and/or phosphorescence, and iv. observing the electromagnetic radiation emitted in response to the exciting irradiation of step iii.

Present invention provides a method for marking hydrocarbon fuels with a marker material and tracking the marked hydrocarbon fuel in a fuel distribution network. The marker material includes an anthrapyridone compound.

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 compound having formula (Ph.sub.3C).sub.mAr(OR).sub.n, wherein Ph represents a phenyl group, Ar is an aromatic ring system having from six to twenty carbon atoms, R is C.sub.1-C.sub.18 alkyl or C.sub.7-C.sub.12 aralkyl, m is one or two, and n is an integer from one to four.

The present disclosure provides compositions, methods, and systems for identifying marked hydrocarbon fluids. These compositions, methods, and systems utilize a gas chromatography marker including a non-pyrrolidinone nitrogen-containing compound. The methods and systems can identify the presence or absence of the gas chromatography marker and/or the non-pyrrolidinone nitrogen-containing compound. The compositions, methods, and systems can optionally utilize a spectroscopic marker.

The present invention relates to a liquid comprising methane and a tracer, and to a slush of liquid and solids comprising methane and a tracer. The invention especially relates to LNG comprising a tracer. The LNG may comprise, in addition to the tracer, an odorant and a carrier for the odorant. The odorant is ethyl acrylate and/or ethyl mercaptan. The carrier for the odorant is propane, n-butane, iso-butane, or a mixture of two or more thereof. The present invention also relates to a process for preparing such a liquid or slush by liquefying a gas comprising methane and a tracer. The invention also relates to a process in which a tracer is added to a methane comprising liquid or slush.

The invention concerns a method of marking a hydrocarbon liquid comprising the

##STR00001##

step of adding to said liquid, as a tracer compound, a compound of Formula I or Formula II: wherein at least one of R.sup.1-R.sup.6 in Formula I and at least one of R.sup.7-R.sup.14 in Formula II is selected from: i. a bromine or fluorine atom; ii. a partially or fully halogenated alkyl group; iii. a branched or cyclic C.sub.4-C.sub.20 alkyl group; iv. an aliphatic substituent linking two positions selected from R.sup.1-R.sup.6 in Formula I to one another or two positions selected from R.sup.7-R.sup.14 in Formula II to one another; or v. a phenyl group substituted with a halogen atom, an aliphatic group or halogenated aliphatic group
and none of R.sup.1-R.sup.6 in Formula I and none of R.sup.7-R.sup.14 in Formula II being a sulphonate group or COOR.sup.15, where R.sup.15 represents H, C.sub.1-C.sub.20 alkyl, C.sub.2-C.sub.20 alkenyl, C.sub.2-C.sub.20 alkynyl, C.sub.3-C.sub.15 cycloalkyl or aryl.

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.