Analytical Sciences

Systemic Analysis of Structures and Contents of Nitrogencontaining Compounds and Other Non-Hydrocarbons in Crude Oils in Conjunction with Chemometric Resolution Technique

Taiming ZHANG,* Yizeng LIANG,* Boyan LI,* Hui CUI,** and Fan GONG*

*College of Chemistry and Chemical Engineering, Central South University, Changsha 410083, P. R. China
**College of Chemistry and Chemical Engineering, HunanUniversity, Changsha 410082, P. R. China

A method is described for the systemic identification and quantitative analysis of nitrogen-containing compounds and other non-hydrocarbons in crude oils. The pre-fractionation of a crude oil sample into 7 fractions was performed by diadsorption column chromatography using neutral aluminum oxide and silica gel. A subsequent high-resolution separation of individual components was achieved by using capillary column gas chromatography, and compound types were detected by a mass spectrometer. In conjunction with a chemometric method, the compounds in the fractions were further resolved or separated, which made it possible to identify some nitrogen-containing compounds and other nonhydrocarbons in crude oils. To a certain extent, this method could relieve the difficulty of classical analysis in identifying those species with very low contents or incompletely separation, particularly in the cases where authentic standards were not available for addition into the unknown samples in order to reveal what indeed existed in them. The structures and contents of 168 nitrogen-containing compounds in one crude sample and 60 non-nitrogen-containing compounds in one of non-hydrocarbon fractions of this oil sample were determined, and the addition-recovery examination of some standard compounds showed that the analytical veracity was satisfactory.

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