Abstract: A method for the determination of hydrocarbon types in light cycle oil (LCO) by automated solid-phase extraction (SPE) coupled with gas chromatography-mass spectrometry was developed. Samples were extracted and pretreated by automatic solid-phase extraction. The extraction conditions, such as the kind of the type of extraction solution, the ratio of sample treatment amount and fixed phase addition amount, the flow rate of elution extraction solution and the volume of air, were optimized. The results showed that when the sample treatment amount was 0.1 mL, the extraction solution of saturated hydrocarbon component was 1.8 mL n-hexane, the extraction solution of aromatic component was 2 mL mixed solution with the volume ratio of dichloromethane to ethanol of 5.0/1.5, the fixed-phase packing in the SPE column was 1.65 g, the flow rate of extraction solution was 1.5 mL/min, the volume of the air eluted by the saturated hydrocarbon component was 0.6 mL, and the volume of the air eluted by the aromatic hydrocarbon component was 18 mL, the recoveries ranged from 98.5% to 100.5% with RSD (n=6)≤7%. The method was suitable for the composition analysis of LCO. The automatic solid-phase extractor was highly automatic, and the analysis efficiency was improved. Under optimized conditions, the analysis results were accurate and repeatable.

Key words: solid-phase extraction, gas chromatography-mass spectrometry, light cycle oil, saturated hydrocarbon, aromatics