| abstract |
A method for marking an oil hydrocarbon, biodiesel fuel or ethanol fuel; said method comprising adding to said petroleum hydrocarbon, biodiesel fuel or ethanol fuel at least one compound having the formula (I) in which R1 and R2 independently represent at least one substituent selected from the group consisting of hydrogen, alkyl C1-C12, C1-C12 alkoxy and nitro; and R3 and R4 independently represent hydrogen, methyl or ethyl. |