Determination by infrared spectroscopy of triacetin content in diesel: A tool for countering designer fuel frauds

Taxation on fuels is an important share of fiscal revenues of most countries. Among the most abundant petrochemicals in the market, gas oil, or diesel, is particularly important, and it is commonly used as fuel for heating systems and for vehicles such as cars and trucks, but also for farm machinery and boats. Due to its wide range of applications and to the fact that most of the final price of diesel is made up of taxes, the phenomenon of designer fuels is increasingly common. Designer fuels are fuels in which some chemical and physical characteristics are fraudulently modified in order to classify them as other goods, e.g. lubricating oils or solvents, which are subject to lower or no taxes. Triacetin is a frequently employed additive for changing the classification of heavy distillates into lubricant oils, and it is therefore important, for a customs office, to be able to assess its presence as quickly and easily as possible, both inside or outside the laboratory. This paper proposes a method based on IR spectroscopy for the detection and quantification of triacetin in diesel, in an inexpensive but effective way. The analytical protocol presented allows a limit of quantification as low as 0.3% v/v, it is robust, precise and accurate enough to yield data useful for the customs agent to take decisions without further lengthy procedures.