GCxGC-HRMS: Combining Multidimensional GC with Ultra High Resolution Time-of-Flight Mass Spectrometry for Comprehensive Analysis of Complex Samples

Significance of the topic

Gas chromatography coupled with high-resolution time-of-flight mass spectrometry (GC-HR-TOFMS) is a leading approach for comprehensive analysis of complex environmental matrices. The introduction of two-dimensional separation (GCxGC) further enhances chromatographic peak capacity, enabling detection of trace-level compounds in samples containing hundreds of analytes.

Objectives and study overview

This study evaluates the performance of a prototype GCxGC-HRT+ instrument incorporating Encoded Frequent Pushing (EFP) to improve duty cycle and sensitivity. It focuses on analyzing Arctic ice samples to demonstrate improvements in analyte coverage, mass accuracy, and dynamic range.

Methodology and instrumentation

The analytical setup comprised

• Agilent 7890B GC with thermal modulation for two-dimensional separation
• LECO Pegasus HRT+ prototype with modified Folded Flight Path (FFP) analyzer and EFP for up to 50,000 resolving power
• Data acquisition at 200 spectra/s to capture narrow GCxGC peak profiles

Sample preparation followed EPA Method 8270. Data acquisition modes included one-dimensional GC with EFP, GCxGC without EFP, and GCxGC with EFP.

Main results and discussion

Key findings

• Over 320 distinct compounds were detected and identified in Arctic ice, surpassing results from conventional GC-HRMS
• EFP enhanced duty cycle by multiplexing up to 20 push pulses per transient, increasing sensitivity up to 10-fold for low-abundance analytes
• Two-dimensional separation resolved coeluting species and reduced spectral interferences, improving mass accuracy and signal quality for trace components

The combination of GCxGC and EFP significantly improved analyte detection limits and dynamic range.

Benefits and practical applications

This approach offers

• Comprehensive profiling of complex environmental samples
• Improved confidence in identification through accurate mass and enhanced separation
• Better detection of trace contaminants in regulatory, QA/QC, and research contexts

Future trends and applications

Emerging developments include

• Integration of GCxGC-HRMS with advanced data processing algorithms for non-target screening
• Real-time monitoring and automated workflows for environmental and industrial quality control
• Application to other complex matrices such as petrochemicals, natural products, and metabolomics

Conclusion

The GCxGC-HRT+ system with EFP demonstrates a powerful platform for in-depth analysis of complex samples. Its enhanced sensitivity, resolution, and mass accuracy position it as an essential tool for environmental scientists and analytical chemists.

References

• Artaev V., Tikhonov G., Pugh S. GCxGC-HRMS: Combining Multidimensional GC with Ultra High Resolution TOFMS for Comprehensive Analysis of Complex Samples. LECO Corporation.
• EPA Method 8270: Semivolatile Organic Compounds by GC/MS.