Size‐exclusion chromatography for the determination of the boiling point distribution of high‐boiling petroleum fractions

The paper describes a new procedure for the determination of boiling point distribution of high‐boiling petroleum fractions using size‐exclusion chromatography with refractive index detection. Thus far, the determination of boiling range distribution by chromatography has been accomplished using simulated distillation with gas chromatography with flame ionization detection. This study revealed that in spite of substantial differences in the separation mechanism and the detection mode, the size‐exclusion chromatography technique yields similar results for the determination of boiling point distribution compared with simulated distillation and novel empty column gas chromatography. The developed procedure using size‐exclusion chromatography has a substantial applicability, especially for the determination of exact final boiling point values for high‐boiling mixtures, for which a standard high‐temperature simulated distillation would have to be used. In this case, the precision of final boiling point determination is low due to the high final temperatures of the gas chromatograph oven and an insufficient thermal stability of both the gas chromatography stationary phase and the sample. Additionally, the use of high‐performance liquid chromatography detectors more sensitive than refractive index detection allows a lower detection limit for high‐molar‐mass aromatic compounds, and thus increases the sensitivity of final boiling point determination.