Solvent Yellow 124 is a yellow

azo dye Azo dyes are organic compounds bearing the functional group R−N=N−R′, in which R and R′ are usually aryl and substituted aryl groups. They are a commercially important family of azo compounds, i.e. compounds containing the C-N=N ...

used in

European Union The European Union (EU) is a supranational political and economic union of member states that are located primarily in Europe. The union has a total area of and an estimated total population of about 447million. The EU has often been des ...

as a

fuel dye Fuel dyes are dyes added to fuels, as in some countries it is required by law to dye a low-tax fuel to deter its use in applications intended for higher-taxed ones. Untaxed fuels are referred to as "dyed", while taxed ones are called "clear" or "w ...

. It is a marker used since August 2002 to distinguish

diesel fuel Diesel fuel , also called diesel oil, is any liquid fuel specifically designed for use in a diesel engine, a type of internal combustion engine in which fuel ignition takes place without a spark as a result of compression of the inlet air and t ...

intended for heating from a higher-

taxed A tax is a compulsory financial charge or some other type of levy imposed on a taxpayer (an individual or legal entity) by a governmental organization in order to fund government spending and various public expenditures (regional, local, or n ...

motor diesel fuel. It is added to fuels not intended for motor vehicles in amounts of 6 mg/L or 7 mg/kg under the name Euromarker.

Euromarker

Solvent Yellow 124 is a dye with structure similar to

Solvent Yellow 56 Solvent Yellow 56 is the organic compound ''N'',''N''-diethyl-''p''-(phenylazo)aniline. It is an azo dye, which has the appearance of a reddish yellow powder. Its EINECS number is 219-616-8.{{Ullmann, first1 = Klaus, last1 = Hunger, first2 = Pet ...

. This dye can be easily hydrolyzed with acids, splitting off the acetal group responsible for its solubility in nonpolar solvents, and yielding a water-soluble form which is easy to extract to water. Like a similar

methyl orange Methyl orange is a pH indicator frequently used in titration because of its clear and distinct color variance at different pH values. Methyl orange shows red color in acidic medium and yellow color in basic medium. Because it changes color at the ...

dye, it changes color to red in acidic pH. It can be easily detected in the fuel at levels as low as 0.3 ppm by

extraction Extraction may refer to: Science and technology Biology and medicine * Comedo extraction, a method of acne treatment * Dental extraction, the surgical removal of a tooth from the mouth Computing and information science * Data extraction, the pro ...

to a diluted

hydrochloric acid Hydrochloric acid, also known as muriatic acid, is an aqueous solution of hydrogen chloride. It is a colorless solution with a distinctive pungent smell. It is classified as a strong acid Acid strength is the tendency of an acid, symbol ...

, allowing detection of the

red diesel Fuel dyes are dyes added to fuels, as in some countries it is required by law to dye a low-tax fuel to deter its use in applications intended for higher-taxed ones. Untaxed fuels are referred to as "dyed", while taxed ones are called "clear" or "w ...

added into motor

diesel Diesel may refer to: * Diesel engine, an internal combustion engine where ignition is caused by compression * Diesel fuel, a liquid fuel used in diesel engines * Diesel locomotive, a railway locomotive in which the prime mover is a diesel engin ...

in amounts as low as 2-3%. Solvent Yellow 124 is intended to be difficult to remove from the fuel in an economical way. The Customs, familiar with various tricks including dual fuel systems with hidden fuel tanks, will take samples from the fuel lines to the engine itself if such equipment is suspected in the car. As the amount of Solvent Yellow 124 added to the fuel is known, by measuring its content in the fuel it is possible to calculate how much of the low-taxed fuel was added to the legal one. Heating oil detection in Diesel fuel

Concerns

The UK government expressed concerns about the possibility of "laundering" the dye out of "illicit" fuel, hampering the detection. Denmark expressed concerns about the dye's toxicity. Euromarker is intended to be replaced later by newer technology markers, such as biological markers or fuel markers with non-destructive analytical methods. These are all special chemicals tailored for the individual products, and perhaps even for individual refineries, allowing the identification of the source of the material by its content of the

molecular marker A molecular marker is a molecule, sampled from some source, that gives information about its source. For example, DNA is a molecular marker that gives information about the organism from which it was taken. For another example, some proteins can be ...

s. In 2014, a new fuel marker more resistant to removal was announced for the United Kingdom.

References

{{Reflist Azo dyes Solvent dyes Vehicle taxes Fuel dyes Acetals