Agilent GC Gasifier Coupled with Agilent 8890 and 8860 Gas Chromatographs for Pressurized Liquid Sample Analysis

Significance of the Topic

Accurate and representative sampling of pressurized liquid hydrocarbons is essential for quality control and regulatory compliance in energy and chemical industries. Fractionation and adsorption issues during vaporization can compromise analytical results.

Objectives and Study Overview

This study evaluates the performance of the Agilent GC gasifier coupled with Agilent 8890 and 8860 gas chromatographs for direct analysis of pressurized liquid samples such as liquefied petroleum gases with oxygenates and high purity 1-butene. Key aims include assessing precision, repeatability, linearity, discrimination effects, carryover, and quantitative accuracy.

Methodology and Instrumentation

The gasification system uses the G3535A gasifier with a 6-port gas sampling valve or a liquid sampling valve. The gasifier features a 150 °C vaporizer, 100 °C heated transfer line, pressure-reducing regulator and deactivated tubing to ensure flash vaporization and minimize adsorption. Samples were analyzed on Agilent 8890 or 8860 GC systems equipped with Al2O3 or Lowox capillary columns and flame ionization detectors. Carrier gas helium and split/splitless injection modes were applied according to tabulated conditions.

Main Results and Discussion

• Repeatability: Twenty consecutive injections of C2–C5 samples yielded retention time RSD <0.1% and peak area RSD <1%.
• Discrimination: Relative response factors for C1–C6 components deviated by less than 10% between gasifier and liquid sampling valve methods, except methane (19%).
• Carryover: Blank runs showed less than 0.1% carryover across C2–C8 compounds.
• Linearity: Calibration curves for hydrocarbons and oxygenates exhibited R2 values above 0.998 over typical concentration ranges.
• Quantitative Accuracy: Analysis of LPG and 1-butene samples met standard method requirements with recoveries between 85% and 115%.

Benefits and Practical Applications

• Simultaneous flash vaporization of all sample components ensures representative analysis.
• Heated and deactivated flow path minimizes condensation and adsorption.
• Integrated control via the GC user interface simplifies operation.
• Suitable for routine QA/QC of LPG composition and purity analysis.

Future Trends and Potential Applications

• Integration with mass spectrometry for enhanced compound identification.
• Automation of sampling routines and data processing with advanced software.
• Extension to heavier hydrocarbons and complex mixtures.
• Application of machine learning for predictive maintenance and method optimization.

Conclusion

The Agilent GC gasifier combined with 8890 or 8860 GC systems offers robust, accurate, and precise analysis of pressurized liquid hydrocarbons and oxygenates. Its design ensures reliable sample vaporization and transfer, meeting industry standards for repeatability, linearity, and quantitative performance.

Instrumentation Used

• Agilent G3535A GC gasifier with vaporizer and heated transfer line
• Agilent 8890 and 8860 gas chromatographs
• 6-port gas sampling valve and liquid sampling valve
• Capillary columns: Al2O3 PLOT/KCL, HP-AL/M, Lowox
• Flame ionization detectors

References

• SH/T 0230-2019 Determination of Composition in Liquefied Petroleum Gases by Gas Chromatography.
• ASTM D2163-14(2019) Standard Test Method for Determination of Hydrocarbons in Liquefied Petroleum Gases and Propane/Propene Mixtures by Gas Chromatography.
• Wan L. Determination of Hydrocarbon and Oxygenate Composition in Liquefied Petroleum Gas Using Agilent Gasifier and 8890 GC. Agilent Technologies; 2020.
• SH/T 1492-2004 1-Butene for Industrial Use – Determination of Purity and Hydrocarbon Impurities by Gas Chromatography.