Dual-Channel GC×GC-FID for Routine Analysis of Total Petroleum Hydrocarbons (TPH-CWG)

New Organic Monitoring Techniques
Oral Presentation

Prepared by L. McGregor1, M. Edwards2, R. Sutherill1, A. Parker1, B. Green1
1 - SepSolve Analytical, Cygnet Park, 4 Swan Court, Peterborough, Cambs, PE7 8GX, United Kingdom
2 - SepSolve Analytical, 826 King Street North, Waterloo, Ontario, N2J 4G8, Canada


Contact Information: [email protected]; 01733669222

ABSTRACT

Until now, the determination of Total Petroleum Hydrocarbons (TPH) in soil has typically involved a convoluted and labour-intensive process. The guidelines set out by the TPH Criteria Working Group (TPH-CWG) state that both the Volatile Petroleum Hydrocarbons (VPH) and Extractable Petroleum Hydrocarbons (EPH) must be characterised.

For analysis of EPH, in the range of C8-C40+, solid phase extraction (SPE) is required to separate the aliphatics and aromatics, usually into hexane and DCM respectively, prior to two separate GC‒FID analyses per sample. While for the VPH, in the narrower range of C5-C10, GC‒MS is often utilised for quantitation of the aromatics and aliphatics in a single run.

The enhanced separation of comprehensive two-dimensional chromatography (GC×GC) negates the requirement for laborious sample fractionation in EPH analysis, as the traditional ‘boiling point’ separation is maintained in the first dimension while the aliphatic and aromatic compounds are separated in the second dimension - saving a significant amount of extraction and processing time, while also reducing consumable costs. Additionally, the use of GC×GC‒FID for VPH analysis enables common co-elutions to be resolved without the need for expensive mass spectrometers.

Fast and confident group-type quantitation can be performed for both methods using simple data processing tools. Stencils are applied to group peaks into chemical classes based on their elution region for real-time reporting of results. The use of flow rather than thermal modulation, also ensures excellent retention time repeatability across large sample batches, enabling automated data processing to be performed with minimal operator intervention.

Furthermore, here we demonstrate a dual-channel configuration, doubling the sample throughput per instrument - increasing productivity, reducing bench space and lowering installation costs, all while meeting the criteria set out in standard methods (e.g., TPH-CWG and Massachusetts Department of Environmental Protection).