Short sequences of DNA have been proposed as suitable tracer molecules to detect fuel adulteration as they potentially offer almost unlimited permutations, parts per trillion addition levels, low toxicity and security from unwanted analysis. In order to test this, a selection of single and double stranded oligonucleotides and plasmid based tracers were designed so as to be non-naturally occurring. Tracer analysis by QPCR in ethanol and gasohol was optimised, allowing the long term stability and precision of quantification to be assessed. The ability of a selected oligonucleotide to resist unauthorised removal in kerosene, gasoline, diesel and gasohol was also investigated. The results show that oligonucleotides do not meet established criteria as a means of tagging fuels in order to prevent adulteration. (C) 2011 Elsevier Ltd. All rights reserved.