AbstractIn this work a practical method is proposed for detection water contamination in gasoline. Methylene blue crystal was added to the gasoline samples and shaked, the blue colour developed in water phase indicating water contamination. Phthalate ester was detected by the GelMS in the water contamined sample. Water contamination was found in one of the three samples tested. The identified hydrocarbons by the GelMS analysis were: 12 aliphatic, 21 aromatic compounds in normal and 9 aliphatic, 19 aromatic compounds in super type of gasoline. Tetra ethyl lead which is usually added to gasoline, was also detected in all the samples ..