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The Determination of Mono- and Polyaromatic Hydrocarbons in Diesel Fuels using Refractive Index Detection

This poster from Knauer illustrates how the aromatic hydrocarbons of diesel fuel can be determined under normal phase conditions, with detection via the refractive index detector AZURA RID 2.1L.

It is well known that the best performance and maximum lifetime of an engine can be reached, when the amount of aromatic hydrocarbons in diesel and aviation turbine fuels is as low as possible. Since the aromatic hydrocarbon content can affect the cetane* number of fuels and cause emissions due to incomplete burning, there are different regulations to protect the environment and public health.

The most common aromatic hydrocarbons found in diesel fuels include 1,2-dimethylbenzene,
fluorene, and phenanthrene, and these compounds were used as the standards.

1-2-Dimethylbenzene molecule
Fluorene molecule
Phenanthrene molecule

The results show that the three aromatic hydrocarbons can be easily separated using normal phase conditions, and that a very high correlation can be achieved at three different concentrations. From this the concentration of the three aromatic hydrocarbons could be calculated, with the 1, 2-dimethylbenzene being by far of the highest concentration

Overlay chromatogram of three replicates
Overlay chromatogram of three replicates
Chromatogram of a diesel fuel sample
Chromatogram of a diesel fuel sample
Calculated amount of identified components in diesel fuel

CLICK HERE for a copy of this poster (pdf 1.26 MB)

For more details on the refractive index detector, AZURA RID 2.1L, used in this work go to Rubicon Science – Detectors for all HPLC & FPLC applications

*(The cetane number, or CN, is an indicator of the combustion speed of diesel fuel and compression needed for ignition. It plays a similar role for diesel as octane rating does for petrol. Generally, diesel engines operate well with a CN from 48 to 50. Fuels with lower cetane number have longer ignition delays, requiring more time for the fuel combustion process to be completed. Hence, higher speed diesel engines operate more effectively with higher cetane number fuels.)

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