Silent marker for an oil product and associated detection method

1. A method for detection of a silent marker in a petroleum product, comprising the steps of:

a) marking the petroleum product with the silent marker, which is an ester derivative of fluorescent material;

b) adding a detection composition to the marked petroleum product, wherein the detection composition contains an enzyme that specifically decomposes the ester moiety of the silent marker; and

c) detecting the presence of the silent marker by measuring the fluorescence generated from step b).

2. The detection method according to claim 1 , wherein said marker is represented by the following Formula I:

wherein, R 1 and R 2 , which are the same or different, are C 4 -C 18 alkyl group.

3. The detection method according to claim 1 , wherein said marker is represented by the following Formula II:

wherein, R 3 is C 4 -C 18 alkyl group; R 4 is methyl or trifluoromethyl; and R 5 is a hydrogen atom, a halogen atom or cyano group.

4. The detection method according to claim 1 , wherein said marker is represented by the following Formula III:

wherein, R 6 and R 7 , which are the same or different, are a C 19 -C 24 alkyl group.

5. The detection method according to claim 1 , wherein said fluorescent material is selected from the group consisting of ester derivatives of 7-hydroxy-4trifluoromethyl coumarin, 7-hydroxy coumarin,3-cyano-7-hydroxy-4-methyl coumarin, 4-hydroxy coumarin, 7hydroxy-4-methyl coumarin and 3-chloro-7-hydroxy-4methyl coumarin, ester derivatives of resorufin, ester derivatives of fluorescein, and a mixture thereof.

6. The detection method according to claim 3 , wherein R 4 is methyl and R 5 is a chlorine atom.

7. The detection method according to claim 2 , wherein each of R 1 and R 2 is a C 15 H 31 group.

8. The detection method according to claim 1 , wherein said marker is added in an amount of 0.01-30 ppm to the petroleum product.

9. The detection method according to claim 1 , wherein said petroleum product is selected from the group consisting of gasoline, liquefied natural gas (LNG), liquefied petroleum gas(LPG), diesel fuel, kerosene and heavy oil.

10. The detection method according to claim 1 , wherein said enzyme selectively hydrolyses the ester moiety of the marker.

11. The detection method according to claim 1 , wherein said enzyme is selected from the group consisting of esterase and cellulase.

12. The detection method according to claim 1 , wherein said enzyme is lipase.

13. The detection method according to claim 1 , wherein said enzyme is linked to at least one polymeric moiety.

14. The detection method according to claim 13 , wherein said enzyme is linked to the polymeric moiety by a linker.

15. The detection method according to claim 14 , wherein said linker is cyanuric chloride.

16. The detection method according to claim 13 , wherein said polymer-linked enzyme is represented by the following general Formula IV;

17. The detection method according to claim 13 , wherein said polymeric moiety is polyethyleneglycol.

18. A method for identifying a petroleum product, comprising the steps of: a) mixing the petroleum product having been marked with a silent marker, which is an ester derivative of fluorescent material, with a composition containing an enzyme that specifically decomposes the ester moiety of the marker to identify the marked petroleum product; and b) measuring the fluorescence generated from step a).

19. The method according to claim 18 , wherein said enzyme selectively hydrolyses the ester moiety of the marker.

20. The method according to claim 18 , wherein said enzyme is selected from the group consisting of esterase and cellulase.

21. The method according to claim 18 , wherein said enzyme is lipase.