A composition comprising a fuel and at least one compound characterized by Formula I:

##STR00001##

wherein X is carbon, oxygen, or sulfur; R.sup.1 and R.sup.2 each independently are hydrogen, a C.sub.1 to C.sub.20 alkyl, or a C.sub.6 to C.sub.10 aryl; R.sup.3 and R.sup.3 each independently are hydrogen or a C.sub.1 to C.sub.4 alkyl; R.sup.4 and R.sup.4 each independently are hydrogen, a C.sub.1 to C.sub.4 alkyl, a C.sub.4 to C.sub.10 cycloalkyl, or a C.sub.6 to C.sub.10 aryl; R.sup.5 and R.sup.5 each independently are a C.sub.4 to C.sub.10 alkyl; R.sup.6 and R.sup.6 each independently are hydrogen or a C.sub.1 to C.sub.6 alkyl; and R.sup.7 and R.sup.7 each independently are hydrogen or a C.sub.1 to C.sub.4 alkyl; and wherein the compound of Formula I when subjected to GC-MS using electron ionization at greater than about 70 eV produces at least one ion having a mass-to-charge ratio of from 300 to 600.

Method of marking a hydrocarbon liquid includes adding to the liquid, a tracer compound of Formula I or II:

##STR00001##

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 and none of R.sup.7-R.sup.14 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 composition comprising a fuel and at least one compound characterized by Formula I: ##STR00001##
wherein X is carbon, oxygen, or sulfur; R.sup.1 and R.sup.2 each independently are hydrogen, a C.sub.1 to C.sub.20 alkyl, or a C.sub.6 to C.sub.10 aryl; R.sup.3 and R.sup.3 each independently are hydrogen or a C.sub.1 to C.sub.4 alkyl; R.sup.4 and R.sup.4 each independently are hydrogen, a C.sub.1 to C.sub.4 alkyl, a C.sub.4 to C.sub.10 cycloalkyl, or a C.sub.6 to C.sub.10 aryl; R.sup.5 and R.sup.5 each independently are a C.sub.4 to C.sub.10 alkyl; R.sup.6 and R.sup.6 each independently are hydrogen or a C.sub.1 to C.sub.6 alkyl; and R.sup.7 and R.sup.7 each independently are hydrogen or a C.sub.1 to C.sub.4 alkyl; and wherein the compound of Formula I when subjected to GC-MS using electron ionization at greater than about 70 eV produces at least one ion having a mass-to-charge ratio of from 300 to 600.

A method for marking a petroleum hydrocarbon or a liquid biologically derived fuel by adding to the petroleum hydrocarbon or liquid biologically derived fuel at least one compound having formula Ar(R.sup.2).sub.m(OR.sup.1).sub.n, wherein Ar is an aromatic ring system having from six to twenty carbon atoms, R.sup.1 is C.sub.1-C.sub.12 alkyl or C.sub.2-C.sub.12 alkenyl, R.sup.2 is C.sub.1-C.sub.12 alkyl or C.sub.3-C.sub.12 alkenyl, m is an integer from zero to five and n is an integer from one to three; wherein each compound of formula Ar(R.sup.2).sub.m(OR.sup.1).sub.n is present at a level from 0.01 ppm to 100 ppm.

A method of marking a hydrocarbon liquid includes the step of adding to the liquid, as a tracer compound, a compound of Formula I:

##STR00001##

wherein at least one of R.sup.1-R.sup.4 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.4 in Formula I to one another; or v. a phenyl group substituted with a halogen atom, an aliphatic group or halogenated aliphatic group. The tracer compounds are resistant to removal from the fuel by chemical laundering or by contact with absorbents such as charcoal.

Method of marking a hydrocarbon liquid includes adding to the liquid, a tracer compound of Formula I or II: ##STR00001##
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 and none of R.sup.7-R.sup.14 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 method of forming a composition comprising contacting a fuel and at least one compound of Formula I: ##STR00001##
wherein X is carbon, oxygen, or sulfur; R.sup.1 and R.sup.2 each independently are hydrogen, a C.sub.1 to C.sub.20 alkyl, or a C.sub.6 to C.sub.10 aryl; R.sup.3 and R.sup.3 each independently are hydrogen or a C.sub.1 to C.sub.4 alkyl; R.sup.4 and R.sup.4 each independently are hydrogen, a C.sub.1 to C.sub.4 alkyl, a C.sub.4 to C.sub.10 cycloalkyl, or a C.sub.6 to C.sub.10 aryl; R.sup.5 and R.sup.5 each independently are a C.sub.4 to C.sub.10 alkyl; R.sup.6 and R.sup.6 each independently are hydrogen or a C.sub.1 to C.sub.6 alkyl; and R.sup.7 and R.sup.7 each independently are hydrogen or C.sub.1 to C.sub.4 alkyl; and wherein the compound of Formula I when subjected to GC-MS using electron ionization at greater than 70 eV produces at least one ion having a mass-to-charge ratio of 300 to 600.

A method of marking a hydrocarbon liquid includes the step of ##STR00001##
adding to the liquid, as a tracer compound, a compound of Formula I:
wherein at least one of R.sup.1-R.sup.4 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.4 in Formula I to one another; or v. a phenyl group substituted with a halogen atom, an aliphatic group or halogenated aliphatic group. The tracer compounds are resistant to removal from the fuel by chemical laundering or by contact with absorbents such as charcoal.

A method for marking a petroleum hydrocarbon or a liquid biologically derived fuel by adding to the petroleum hydrocarbon or liquid biologically derived fuel a compound having formula C{Ph(R.sup.1).sub.i(OR.sup.2).sub.j}.sub.2{Ph(R.sup.3).sub.m}{OR.sup.4).sub.n}{Ph(R.sup.5).sub.o(OR.sup.6).sub.p}, wherein Ph represents a benzene ring, R.sup.1, R.sup.3 and R.sup.5 independently are C.sub.1-C.sub.18 alkyl or C.sub.4-C.sub.18 heteroalkyl; R.sup.2, R.sup.4 and R.sup.6 independently are C.sub.1-C.sub.18 alkyl or C.sub.4-C.sub.18 heteroalkyl, i, j, m, n, o and p independently are zero, one or two. Each compound having formula C{Ph(R.sup.1).sub.i(OR.sup.2).sub.j}.sub.2{Ph(R.sup.3).sub.m(OR.sup.4).sub.n}{Ph(R.sup.5).sub.o(0R.sup.6).sub.p} is present at a level from 0.01 ppm to 20 ppm.

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.