Environmental Total Petroleum Hydrocarbon (TPH) Analyser

Significance of the Topic

Total petroleum hydrocarbons (TPH) span a diverse set of aliphatic and aromatic compounds originating from crude oil, fuel products and biofuels. Accurate TPH analysis is vital for environmental monitoring, risk assessment and remediation of soil and water contamination. Differentiation of hydrocarbon classes and fractions supports toxicity evaluation, regulatory compliance and long-term impact studies.

Study Objectives and Overview

This application note addresses the challenges of minimizing sample preparation, consolidating analytic methods and improving data quality for TPH analysis. Key goals included:

• Reducing preparation steps and associated errors
• Streamlining methods into a single workflow
• Visualizing and reporting precise banding of fractions and compound classes
• Ensuring UKAS and MCERTS accreditation for C8–C40 hydrocarbons

Methodology and Instrumentation

Samples of soil and water were extracted in pentane/dichloromethane, with calibration standards prepared from 40 to 4 000 µg/mL TPH. Extracts were injected by a low-split flow 7693A autosampler using hydrogen carrier gas. A two-dimensional gas chromatography approach (GC×GC) separated aliphatics from aromatics, applying a predefined template for banding, fractions and individual component integration. Data were processed automatically using GC Image software.

Used Instrumentation

• Agilent 7890 GC base system
• 7693A autosampler with split/splitless injector
• Flame Ionisation Detector (FID)
• Agilent flow modulator for GC×GC implementation
• GC Image software for 2D visualization and data processing

Main Results and Discussion

The optimized GC×GC method delivered:

• Clear separation of aliphatic and aromatic hydrocarbon bands
• Well-defined banding of petrol, kerosene, diesel and heavier fractions
• Linearity of 5–5 000 ppm TPH with R² > 0.995
• Retention time precision (%RSD < 0.01 %) and repeatability (< 1 %)
• Recovery of 98–101 % for spiked soils (500–2 500 ppm)

The two-dimensional plot enabled unambiguous identification of compound classes and facilitated targeted compound reporting without manual peak picking.

Benefits and Practical Applications of the Method

This turnkey analyzer reduces operator skill requirements and accelerates time to result. It supports:

• Routine TPH monitoring in environmental laboratories
• Regulatory reporting under UKAS and MCERTS standards
• Distinction of weathered or biodegraded products
• Flexible tuning for C5–C44 hydrocarbon ranges

Future Trends and Opportunities

Advances are expected in real-time field-deployable GC×GC systems, integration with mass spectrometry for compound confirmation and coupling with automated data analytics and machine learning. Enhanced spectral libraries and artificial intelligence-driven interpretation will further increase throughput and data insight.

Conclusion

The described GC×GC-FID approach provides a robust, accredited solution for comprehensive TPH analysis. By combining advanced modulation with infrared-capable detection software, it streamlines workflows, improves data quality and supports reliable environmental hydrocarbon monitoring.