New Application of Solid-phase Microextraction (SPME) in Analyzing Volatile Hydrocarbons (C1–C9) in Natural Gas
Current Research and Development in Chemistry Vol. 1,
Page 29-41
Abstract
Solid-phase microextraction (SPME) coupled with gas chromatography-isotope ratio mass spectrometry (GC-IRMS) has already been applied to collect and identify volatile light hydrocarbons in oil and source rocks. However, this technology has not yet been used to analyze volatile light hydrocarbons in dry gas (natural gas with C1/C2+>95%). In this study, we developed a method to measure the molecular and carbon isotope composition of natural gas using Divinylbenzene/ Carboxen/Polydimethylsiloxane (DVB/CAR/PDMS) fiber. This fiber proved to be suitable for extracting C1–C9 hydrocarbons from natural gas without inducing carbon isotopic fractionation. Notably, the extraction coefficients of the analytes were not the same, but rather increased with the increasing carbon number of the hydrocarbons. Nevertheless, we successfully identified 24 hydrocarbons from the in-lab standard natural gas, while also obtaining the carbon isotope composition of C1 to C9 hydrocarbons with satisfying repeatability. The relative standard deviation (RSD) of the molecular composition data was in the range of 0.06–0.74%, with the RSD of the carbon isotope composition data not exceeding 1‰. Finally, seven natural gas samples, collected from different sedimentary basins, were successfully analyzed and the stable carbon isotope compositions of C1–C9 hydrocarbons present in these were determined through this method.
Keywords:
- Solid-phase microextraction
- volatile hydrocarbons
- natural gas
- GC-IRMS
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