Tracer to gasoline, diesel fuel and heating fuel
Summary and conclusions
In a search for an applicable tracer or marker for gasoline, diesel fuel and heating fuel, 19 known colorants have been evaluated. It is recognised that only little information on the physic-chemical properties, and effects on human health and the environment of the evaluated substances exists. Because of the lack of sufficient data, QSAR estimations have been made.
A further 19 organic substances not known to be naturally occurring have been selected, based on properties equivalent to the substances contained in the fuels. These 19 organic substances were also evaluated based on their properties, and effects on human health and the environment.
Based on the evaluation procedure five substances were selected for a more thorough evaluation, and finally three substances were selected as acceptable candidates.
The three substances are
 | Solvent Red 111 |
| 2-Aminoanthraquinon |
| Propyl parabene |
For all substances, it is evaluated that their properties made them fit to the purpose, and that their effect on human health and the environment would not increase the toxicity or other effects already intrinsic in fuels.
For analytical methods, it is evaluated that GC/MS would be a sufficient, valid, and reliable detection method. It is a method, which is already in use when measuring soil pollution. This method is efficient for detection of propyl parabene. Solvent Red 111 and 2-Aminoanthraquinon can be detected by photometry methods. A concentration of the tracer of 50 ppm is considered sufficient to assure an acceptable recovery from polluted soil. The concentration of tracer needed so that it can be identified in soil is very uncertain, and it is necessary to conduct practical tests in order to establish these concentrations. It has to be mentioned that a level of about 50 ppm is higher than for tracers in other situations.
On the basis of the selection methods and the assessments, it is evaluated that all the selected substances will behave, and will be degraded, at the same rate, as the fuels selected in the terrestrial environment.
Solvent Red 111 and 2-aminoanthraquinone are both anthraquinone derivates, which are already known by the petrochemical industry and are used for colouring and marking purposes. No problems in their use and handling are anticipated.
Propyl parabene and cyclohexyl acetate are monocyclic substances and no problems in their use are expected. However, cyclohexyl acetate has a high vapour pressure, which is estimated to make it behave like the lighter fractions of the fuel components. This could mean the persistence in the soil is too short for the purpose intended.