Determining petrochemical composition by GC×GC–TOF MS/FID: Reliable, automated group-type analysis

Determining petrochemical composition by GC×GC–TOF MS/FID: Reliable, automated group-type analysis

Characterising petrochemicals by assigning individual analytes to structurally-related groups in a GC×GC workflow has great potential to improve the speed with which petrochemical compositions can be assessed.

Introduction

Precise characterisation of petroleum-derived fuels is crucial for quality control, to understand the reactions that take place during refining processes, and also for environmental monitoring. However, individually identifying the thousands of components present in these complex samples can be impractical.[1,2]

Group-type analysis using comprehensive two-dimensional gas chromatography (GC×GC) offers a practical approach to this problem. The vastly expanded separation space of GC×GC (compared to conventional chromatography) reduces the incidence of co-elution, while the ‘roof-tiling’ effect facilitates the simple division of hydrocarbons into structurally-similar classes. This approach is now widely used for the analysis of petrochemicals, typically in conjunction with flame ionisation detection (FID) for ‘gold-standard’ quantitation.

However, difficulties can arise when compound classes overlap, and for this reason time-of-flight mass spectrometry (TOF MS) has become important to identify class boundaries accurately, and so generate ‘stencils’ that can be reliably applied to unknown samples (acquired on either TOF MS or FID).