On-Site Analysis of Gasoline Range Organics (GRO) in Soil and Groundwater Using Field Portable Purge and Trap GC / FID / PID

Importance of the Topic

Gasoline range organics (GRO) released from leaking underground storage tanks and transportation incidents pose significant risks to soil and groundwater quality. Rapid on-site analysis accelerates remediation, reduces costs tied to sample transport, and supports real-time plume tracking during spill response.

Study Objectives and Overview

This application note evaluates the performance of field-portable purge and trap gas chromatography systems (Buck Scientific Series 300 and 910) equipped with flame ionization (FID) and photoionization detectors (PID) for low-level GRO detection in soil and groundwater.

Methodology and Instrumentation

The approach employs a built-in purge and trap module compliant with EPA methods. Disposable sparging vessels prevent cross-contamination and speed sample turnover. Samples are analyzed either by direct injection (typical elution under 12 minutes) or by purge and trap (under 20 minutes). Separation is achieved on a single GC column. Detectors include:

• Flame ionization detector (FID) for total hydrocarbons
• Photoionization detector (PID) for enhanced sensitivity to BTEX aromatics

The GC is controlled by PeakSimple II software on an IBM-compatible computer.

Main Results and Discussion

Detector performance metrics demonstrate high sensitivity and broad linearity:

• FID sensitivity: 5.9 mV·s/ng hydrocarbon; detection limit 0.458 mg·L⁻¹ as diesel range organics; linear range 10⁷
• PID sensitivity: 18.02 mV·s/pg benzene; detection limit 0.004 mg·L⁻¹ as benzene; linear range 10⁵

The PID’s enhanced detection of BTEX compounds allows positive identification on a single analytical column. Rapid cycle times and disposable components minimize operational bottlenecks and laboratory backlog.

Benefits and Practical Applications of the Method

• On-site rapid screening of soil and groundwater without sample transport delays
• Low detection limits for regulatory compliance and QA/QC applications
• Disposable sparging vessels eliminate cross-contamination and reduce cleanup time
• Portable system design supports continuous plume tracking during remediation projects
• Flexible analysis modes (direct injection or purge and trap) adapt to field requirements

Future Trends and Possibilities for Use

Advances in portable GC technology and detector miniaturization, integration with mass spectrometry, wireless data transmission, and IoT connectivity will further enhance in-field environmental monitoring. Automated preconcentration modules and AI-assisted data interpretation can improve sensitivity, selectivity, and decision support in real time.

Conclusion

Field-portable purge and trap GC/FID/PID systems provide rapid, sensitive, and reliable GRO analysis directly at contaminated sites. This capability streamlines environmental assessments, accelerates remediation decisions, and reduces laboratory turnaround times.