Bisphenol A compounds as markers for liquid hydrocarbons and other fuels and oils

1. 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 having formula (I),

wherein R 1 and R 2 independently represent hydrogen or C 1 -C 4 alkyl groups, and G represents hydrogen or at least one substituent selected from the group consisting of C 1 -C 18 alkyl and C 1 -C 18 alkoxy.

2. The method of claim 1 in which each compound of formula (I) is present at a level from 0.01 ppm to 20 ppm.

3. The method of claim 2 in which R 1 and R 2 represent hydrogen or methyl.

4. The method of claim 3 in which G represents hydrogen or at least one substituent selected from the group consisting of C 1 -C 8 alkyl and C 1 -C 8 alkoxy.

5. The method of claim 4 in which R 1 and R 2 represent hydrogen.

6. The method of claim 5 in which each compound of formula (I) is present at a level from 0.01 ppm to 10 ppm.

7. The method of claim 6 in which G represents hydrogen or one or two substituents selected from the group consisting of C 1 -C 6 alkyl and C 1 -C 6 alkoxy.

8. The method of claim 7 in which said petroleum hydrocarbon or liquid biologically derived fuel is a petroleum hydrocarbon, biodiesel fuel or ethanol fuel.

9. The method of claim 8 in which G represents one or two substituents selected from the group consisting of C 1 -C 4 alkyl and C 1 -C 4 alkoxy.

10. The method of claim 9 in which G represents one or two substituents selected from the group consisting of methyl and ethyl, and each compound of formula (I) is present at a level from 0.02 ppm to 8 ppm.