Quantitative separation of aliphatic and aromatic hydrocarbons using silver ion--silica solid-phase extraction

Area of Science:

• Geochemistry
• Analytical Chemistry
• Petroleum Science

Background:

• Crude oil analysis requires effective separation of aliphatic and aromatic hydrocarbon fractions.
• Traditional liquid chromatography methods can struggle with efficient separation, especially for complex mixtures and volatile compounds.

Purpose of the Study:

• To develop and evaluate a solid-phase extraction (SPE) method for separating aliphatic and aromatic hydrocarbons from crude oils.
• To assess the versatility and efficiency of the SPE method using diverse crude oil samples.

Main Methods:

• Development of a solid-phase extraction (SPE) method utilizing silver nitrate-impregnated silica.
• Application of the SPE method to light (North Sea) and heavy (Orcutt field) crude oils.
• Evaluation of separation efficiency through geochemical parameter analysis and quantification of specific hydrocarbon classes.

Main Results:

• The SPE method demonstrated excellent reproducibility for geochemical parameters in both aliphatic and aromatic hydrocarbon fractions.
• SPE efficiently separated monoaromatic steroid hydrocarbons, often challenging for traditional methods.
• The technique showed selectivity and efficiency comparable to silica gel Thin Layer Chromatography (TLC).
• Limited losses of volatile compounds like naphthalene were observed due to the sample remaining in solvent.

Conclusions:

• Solid-phase extraction (SPE) provides a rapid and reproducible method for processing large numbers of crude oil samples.
• The developed SPE technique is versatile and efficient for separating hydrocarbon classes in various crude oil types.
• SPE offers an advantageous alternative to traditional methods for hydrocarbon analysis in petroleum geochemistry.