| abstract |
A method for marking a liquid petroleum hydrocarbon. The methodncomprises adding to the liquid petroleum hydrocarbon at least one substitutednanthraquinone dye having formula (I)n nwherein X is O or S; Y is O, NR 7 or S; R 1 and R 2 independently are hydrogen,nalkyl, aryl, aralkyl, heteroalkyl, heterocyclic or alkanoyl; R 3 and R 5 nindependently are alkyl, aryl, aralkyl, heteroalkyl or heterocyclic; R 4 and R 6 nindependently are hydrogen or alkyl; R 7 is hydrogen or alkyl; and wherein thensubstituted anthraquinone dye(s) has an absorption maximum in the range fromn600 nm to 750 nm. |