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The supercritical fluid extraction method allows petroleum refiners to produce high-value vacuum gas oil. Petroleum refiners can separate bottom-of-the-barrel petroleum residua into 20 narrow subfractions related to the fraction's molecular weight. This method helps petroleum refiners better understand the chemistry of the feedstock. Other methods used in heavy petroleum feedstock fractioning include sequential extraction fractionation and conventional vacuum distillation., The ability to process bottom-of-the-barrel fractions is strongly dependent on the chemistry of the feedstocks. But, because of the complexity of residue species there is no standard analytical tool or [...]

Polyhydroxylflavonoids, isorhamnetin, kampcetin, quercetin, and fisetin are efficiently separated using supercritical carbon dioxide modified by ethanol with phosphoric acid as an additive on packed-column supercritical fluid chromatography. The effect of the silica-based stationary phase, composition of mobile phase, temperature, and pressure are investigated. The addition of phosphoric acid as a polar additive improves peak shapes.