Petroleum products are subject to adulteration and tax evasion worldwide. These illegal practices deprive governments and legitimate businesses of profits and may be hazardous to users, as well as the environment. Such deception can also cause harm, sometimes irreparable harm, including, for example, to the brand name or brand image of the producer of the original product. Significant commercial gain can also be obtained by counterfeiters through the dilution of the original products with a readily available, less expensive material. Markers for petroleum products that provide a technique to determine the authenticity of the product are known in the art. For instance, petroleum products can be tagged for identification purposes with coloring agents to provide a distinct color visually perceptible to the naked eye.
Unlike most hydrocarbon fuels, liquefied petroleum gas (LPG) is stored in a liquid form and used in a gaseous form. When an outlet valve on an LPG source (for example, a tank or cylinder) is opened, gas pressure from the liquid in the source causes gas to flow without a pump. Pressure requirements for different applications may be met by use of an appropriate pressure regulator with the source.
LPG may be sold as bottled gas or delivered to and stored in above-ground or below-ground tanks for use in households, road transportation, industry, agriculture, and the energy sector. The relatively low price of LPG has resulted in increased usage of this fuel for engines. Suppliers that do not pay required taxes offer cost advantages through unfair practices, without necessarily adhering to safety and maintenance standards. In some cases, bottled gas cylinders are refilled illegally, increasing the risk of explosion.
Various actions have been taken to counteract these illegal practices. In some cases, security features for LPG cylinders are implemented to reduce counterfeiting of these cylinders. In other cases, markers are added to LPG at relatively high ppm levels to indicate, for example, an origin or intended use of the LPG. This high marker concentration can lead to fouling of nozzles and injection systems. The markers may include, for example, fluorescent material. Conventional sampling methods generally involve removing a sample of the hydrocarbon fluid and testing for the presence of a marker to authenticate the source of the hydrocarbon fluid.