Abstract: A liquid hydrocarbon fuel composition comprises at least one tagging agent and a mixture of hydrocarbon components having boiling points in the range of about 100 degrees F. to about 800 degrees F. The tagging agent is present at a concentration in the range of from about 0.5 ppb to about 500 ppb. The tagging agent is elutable by chromatographic analysis of the liquid hydrocarbon fuel composition apart from the hydrocarbon components of the fuel composition. The tagging agent is formed from an organic compound containing elements found at natural isotopic abundance. Preferably, two or more tagging agents are employed in the fuel so that each fuel composition can be assigned a unique tagging agent composition. Analysis techniques are also disclosed.

Abstract: A method is disclosed for identifying the source of a transported chemical shipment. The method employs either a chemical element or an organic compound with one or more atoms that are non-radioactive isotopes generally not found in nature. A small quantity of the isotopic compound is introduced into the storage vessel containing the chemical to be transported prior to shipment of the chemical. Upon arrival at its destination point, a sample of the chemical shipment is analyzed. Matching the isotopic compound found in the chemical with the isotopic compound introduced into the storage vessel prior to shipment is indicative that the shipped chemical is identical to the chemical received. Non-radioactive materials may further be employed for detecting the source of a newly introduced contaminant in a water supply. The chemical substance may be a non-radioactive isotope of the chemical shipment being transported.