| Abstract
| - Crude oils can be described compositionally by a number of methods. SARA analysis is widelyused to divide crude oil components according to their polarizability and polarity using a familyof related analytical techniques. Problems arise because the analytical techniques do notnecessarily produce identical results. Users of the data, however, rarely distinguish between thedifferent techniques, assuming that SARA fraction values generated by any of the commonlyused methods are essentially interchangeable. We examine this assumption for medium gravitycrude oils and three SARA analysis methods: gravity-driven chromatographic separation, thin-layer chromatography (TLC), and high-pressure liquid chromatography (HPLC). Results for asuite of six crude oil samples show that a significant volume of volatile material that containsboth saturates and aromatics is lost in the TLC analysis. An improved HPLC method is introducedthat gives analyses comparable to the ASTM-recommended chromatographic method in less timethan that required for TLC analysis. An internal consistency test is recommended for evaluatingSARA fraction data.
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