A novel method for quantitative analysis of diamondoids in petroleum samples

A new method for the quantitative analysis of diamondoid hydrocarbons in petroleum geological samples was established using comprehensive two-dimensional gas chromatography-flame ionization detector (GC×GC-FID). The process included the pretreatment of sample followed by the qualitative analysis of diamondoid hydrocarbons using two-dimensional gas chromatography with time-of-flight mass spectrometry (GC×GC-TOFMS). The diamondoid hydrocarbons could be well separated using the orthogonal separation characteristics of GC×GC, The original separation method of saturated hydrocarbon fraction in petroleum samples was improved in this study in order to reduce the loss of low-carbon diamondoid hydrocarbons in the pretreatment process. A new pretreatment method for saturated hydrocarbon by small column chromatography was established. There were many advantages such as lower sample costs, short analysis time and little consumption of reagents. The recovery of diamondoid hydrocarbons was satisfied for chromatography quantitative analysis. Compared to the traditional internal standard semi-quantitative method by gas chromatography-mass spectrometry (GC-MS), this method had high resolution and lower requirements for internal standards. The quantitative results of diamondoids could be obtained using only one certified reference material of deuterated adamantane. Moreover, the repeatability was good. The relative standard deviation (RSD, n=7) was less than 5%, which could meet the analytical requirements of a complicated system.