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 diaryl ether, 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 or hydrocarbyloxy; 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 disclosure provides dyes for marking hydrocarbon compositions. More particularly, the disclosure relates to non-mutagenic dyes for marking hydrocarbon compositions.

A compound of formula (I):

##STR00001##

wherein p is at least 1, n is at least 1 and less than or equal to p; Ar is a polycyclic aromatic moiety, R.sup.1 is hydrogen or an optionally substituted hydrocarbyl group and each of R.sup.2, R.sup.3 and R.sup.4 is independently an optionally substituted hydrocarbyl group, provided that at least one of R.sup.2, R.sup.3 and R.sup.4 has at least 6 carbon atoms.

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.

A marking method which is a method of marking a product having a distillation range is disclosed. The method comprises the step of adding to said product a first marker, a second marker and optionally one or more further markers. Each marker has a distillation range including a minimum boiling point (Min BP), a maximum boiling point (Max BP) and a maximum distillation boiling point (Max DBP) which is the temperature at which the maximum volume of the marker distils. Each marker has a different distillation range from each other marker and at least one marker has a Max DBP which is within the distillation range of the product. The first marker has a distillation range in the marked product which extends over the whole of the product distillation range.

A Liquid, comprising an hydrophobic flavonoid derivative electrochemically non-active, that is capable of restoring its electrochemical activity, the concentration of the flavonoid derivative being 10 ppm by weight or less, and an organic substance in an amount of 90% by weight or more.

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

A fuel additive for fuel formulations comprising calcium sulfonates in an amount effective to limit or eliminate valve seat recession in engines utilizing such fuel formulations. The fuel additive may also include a detergent, particularly in an amount to enhance the VSR limiting effect of the calcium sulfonates. Also included are fuel formulations containing calcium sulfonates in a concentration effective to limit vale seat recession in engines utilizing the fuel formulations. Methods for treating VSR in piston engines are also provided.

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.