Chromatographic profiling of heavy petroleum products by AMD-densitometry. Repeatability, factors influencing separation and some examples of application

Jarne Lardiés, Carmen
International Symposium for Thin-Layer Chromatography
Participation type: 
Lyon (Francia)

Automated Multiple Development (AMD) can be used for semi-detailed chromatographic
characterization of heavy petroleum products. An optimized 20-step, THF-DCM-n-heptane gradient
has been used for profiling a variety of samples that covers the whole range of petroleum heavy
Peak migration distances, chromatographic profiles, and fluorescence intensity signals obtained
using this method have shown to be repeatable (intra- and inter-plate in the same laboratory) and
reproducible (in two different laboratories).
Factors influencing separation have been studied. THF, coming from either mobile phase or plate
cleaning solvent, plays a crucial role in the separation of the “Resins” zone of chromatogram. A
mechanism previously proposed by Scott explains THF role on the behaviour of heavy
hydrocarbon compounds.
Although this separation does not provide a complete molecular resolution of heavy petroleum
products, the resulting profiles adequately represent the complexity of the analyte, and can provide
a useful information for identification, comparison purposes, or for evaluating the effect of process
variables on a crude oil. Some examples of application are presented. In the case of bitumes,
different profiles have been obtained in function of their origin. A deasphalting process of an extra-
heavy raw oil has also been monitored, showing different profiles for the crude oil and its derived
deasphalted products under different conditions.