IP 548: Determination of aromatic hydrocarbon types in middle distillates - High performance liquid chromatography method with refractive index detection

Overview:

Scope

This Standard specifies a method for the determination of the content of mono-aromatic, di-aromatic and tri+ -aromatic hydrocarbons in diesel fuels and petroleum distillates boiling in the range of 150 °C to 400 °C. The total content of aromatic compounds is calculated from the sum of the corresponding individual hydrocarbon types.

Compounds containing sulfur, nitrogen and oxygen may interfere in the determination; mono-alkenes do not interfere but conjugated di-alkenes and polyalkenes, if present, may do so.

NOTE 1 - The precision of the method has been established for diesel fuels and their blending components containing 4 % (m/m) to 40 % (m/m) mono-aromatic hydrocarbons, 0 % (m/m) to 20 % (m/m) di-aromatic hydrocarbons, 0 % (m/m) to 6 % (m/m) tri+-aromatic hydrocarbons, 0 to 26 % (m/m) polycyclic aromatic hydrocarbons, and 4 % (m/m) to 65 % (m/m) total aromatic hydrocarbons.

NOTE 2 - By convention, this standard defines the aromatic hydrocarbon types on the basis of their elution characteristics from the specified liquid chromatography column relative to model aromatic compounds. Quantification is by external calibration using a single aromatic compound, which may or may not be representative of the aromatics in the sample, for each aromatic hydrocarbon type. Alternative techniques and methods may classify and quantify individual aromatic hydrocarbon types differently.

NOTE 3 - Fatty Acid Methyl Esters (FAME), if present, interfere with tri+-aromatic hydrocarbons. If this method is used for diesel containing FAME, the amount of tri+-aromatics will be over estimated.