Comprehensive Two-Dimensional Gas Chromatography to Assess Petroleum Product Weathering

Abstract

Petroleum products are highly diverse, complex organic mixtures often comprising thousands of hydrocarbon compounds. When released into the environment, these complex mixtures are simultaneously subjected to physical, chemical, and biological weathering processes. Quantifying the impact of these processes requires methods to resolve changes in the concentrations of the constituent components. Comprehensive twodimensional gas chromatography (GC
GC) is an effective tool for the separation and analysis of complex organicmixtures and is well suited to this task. The separation of compounds in two dimensions based on their affinity for different stationary phases results in greater chromatographic peak capacity and allows for the estimation of physical–chemical properties relevant to environmental partitioning. Recent advances in instrumentation and data analysis tools have enabled the expanded use of GC
GC in analysis of petroleum products. However, the application of GC
GC to the analysis of petroleum product weathering has been limited by a lack of widely available, robust data analysis tools. Here we present a highly reliable instrument method for the analysis of crude oil, refined petroleum products, and weathered petroleum residues.We then describe a recommended method for fingerprinting ofweathered petroleumresidues and comparison to source materials. Finally, we describe a set of recently developed, freely available computer algorithms for the qualitative and quantitative analysis of petroleum product weathering processes. The described methods support quantitative estimates of the contributions of evaporation and dissolution to the weathering of oil samples.