Florida TRPH Standard on Rxi®-1HT (15 m x 0.25 mm x 0.10 μm)

Importance of the Topic

Analysis of total petroleum hydrocarbons (TPH) in environmental and industrial samples is crucial for compliance and quality control. Reliable separation of a broad range of hydrocarbon constituents from C8 to C40 supports assessments of fuel contamination, soil pollution, and process streams. This standard method using Rxi®-1HT column enables rapid and reproducible profiling of hydrocarbon distributions.

Objectives and Study Overview

This application note details the chromatographic performance of the Florida TPH standard on a high-temperature Rxi®-1HT column. The goal was to evaluate retention behavior, resolution, and run time efficiency across a homologous series of n-alkanes (C8–C40) under optimized temperature programming and hydrogen carrier gas conditions.

Methodology and Instrumentation

• Column: Rxi®-1HT, 15 m × 0.25 mm ID, 0.10 µm film thickness (actual length 15.7 m).
• Sample: Florida TPH standard, 500 ng/µL in hexane, 1 µL injected (split 250:1).
• Injector: Premium 4 mm precision liner with wool, 275 °C.
• Oven program: 40 °C hold 0.1 min, ramp 20 °C/min to 400 °C, hold 1.9 min.
• Carrier gas: H₂ at 1.75 mL/min constant flow.
• Detector: FID at 420 °C with N₂ make-up (50 mL/min), H₂ 40 mL/min, air 450 mL/min.
• Instrumentation: Agilent/HP 6890 GC, data rate 20 Hz.

Main Results and Discussion

The chromatogram demonstrated baseline separation of n-alkanes from C8 (tR 60.7 s) through C40 (tR 840.2 s) within a 14-minute runtime. Retention times increased linearly with carbon number, confirming the column’s high-temperature stability and consistent selectivity. Resolution between adjacent peaks exceeded critical values (>1.5) across the series, indicating efficient elution and minimal co-elution risk. The hydrogen carrier gas provided faster analysis without sacrificing peak shape or resolution.

Benefits and Practical Applications

• Rapid profiling of hydrocarbon mixtures for environmental monitoring and spill assessment.
• High-temperature GC stability reduces cycle time for heavy hydrocarbon analysis.
• Compatibility with standard FID detection ensures quantitative robustness.
• Suitable for QA/QC in petrochemical manufacturing and regulatory compliance.

Future Trends and Potential Applications

Advances in column technology and carrier gas optimization may further reduce analysis time and increase robustness. Integration with high-resolution mass spectrometry could enhance identification of complex hydrocarbon isomers. Automated data processing and real-time monitoring platforms will expand the method’s use in on-site environmental diagnostics and process control.

Conclusion

The study confirms that the Rxi®-1HT column delivers rapid, high-resolution separation of C8–C40 n-alkanes using hydrogen carrier gas and FID detection. This methodology supports efficient TPH analysis for diverse applications in environmental, industrial, and regulatory laboratories.