A Detailed Look at the Saturate Fractions of Different Crude Oils Using Direct Analysis by Ultrahigh Resolution Mass Spectrometry (UHRMS)

Abstract

SARA (Saturates, Aromatics, Resins, Asphaltenes) fractionation is a common simplification technique used for decades in petrochemical analysis. A large number of studies are dealing with the different fractions, but overall, the saturate fraction is strongly neglected. Of the very few available studies on the saturates fraction, almost all have been performed using gas chromatographic (GC) techniques. This discriminates the results of the saturate fraction especially since non-volatile, high molecular weight and polar constituents are mostly excluded. Here, for the first time, saturate fractions of different crude oils from different origins are analyzed using direct infusion ultrahigh resolution mass spectrometry (UHRMS), to study the compositions on a molecular level. Electrospray (ESI), atmospheric pressure chemical ionization (APCI) and atmospheric pressure photoionization (APPI) are used in positive mode. The observed results show the presence of different heteroatom containing classes, with different chemical identities (i.e., presence of thiophenes, mercaptans and cyclic-sulfides in case of S-containing compounds). These results show the high affinity of some specific compounds towards different ionization techniques. Finally, the saturate fraction is shown to include much more than only volatile, saturated and aliphatic compounds. The detected compounds in this fraction present a very wide variety, not only in terms of their carbon atoms per molecule and their aromaticity, but also with regard to their functional groups and structural arrangements.

Influence of High-Molecular n-Alkane Associates on Rheological Behavior of the Crude Oil Residue

“…The observed paraffin crystals in refs and are non-linear (not needle-shaped) elongated structure with superficial roughness that can be attributed to the crystallization interferes such as asphaltenes, resins, and different organic chains. Thus, we suggest that n -alkane associates can be considered as coacervates with specific shells, internal composition, and structure, which are not common for the dispersed medium.…”

The Origin, Physicochemical Properties, and Removal Technology of Metallic Porphyrins from Crude Oils

“…The residue is packed as the stationary phase of the chromatography column and subsequently eluted stepwise using n-hexane:cyclohexane 1:1 v/v, nhexane:toluene 7:3 v/v, carbon tetrachloride:chloroform 7:3 v/v, and acetonitrile:methanol 1:1 v/v to respectively obtain the saturated (A1), aromatic (A2), resin (A3), and asphaltene (A4) fractions of crude oil. Preconcentration of metallic porphyrins using the SARA method has been reported for Venezuela crude oil, Russia Tatarstan crude oil, Kuwait crude oil, Athabasca oil sand, Utah oil sand, China Qingchuan gilsonite oil, Texas shale oil, heavy Eurasian oil, and light East Asian oil [16,[36][37].…”

The Preparation of Novel Amino Acid Imidazole Ionic Liquids and Their Application as Stationary Phase for Capillary Gas Chromatographic Separations

“…[1] It has been extensively used in petrochemical, materials, biological medicine, environmental pollution detection, food safety evaluation and pharmaceutical anlaysis fields because of its inherent advantages of simplicity, high resolution, high selectivity, high sensitivity, short analysis time and low cost. [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] In GC, chromatographic stationary phase plays a key role in the highresolution separation of analytes. [17][18][19] Therefore, the development of high performance chromatographic stationary phase has important theoretical and practical significance.…”