Soft Ionization GC Coupling to LC-MS Systems

Importance of the topic

Gas chromatography (GC) paired with mass spectrometry (MS) is a cornerstone of routine analytical practice, yet many sample matrices demand both GC-MS and liquid chromatography-MS (LC-MS) to span the full spectrum of target analytes. Traditional approaches requiring separate instrumentation drive up capital expenditure, laboratory footprint and maintenance efforts. The integration of soft ionization GC coupling on LC-MS platforms addresses these challenges by uniting comprehensive analyte coverage with high sensitivity and selectivity in a single workflow.

Goals and study overview

This work presents the SICRIT® soft plasma ionization source as a versatile, cost-effective interface enabling direct GC analysis on existing LC-MS systems. Key objectives include:

• Demonstrating seamless coupling of any GC or GCxGC system to high-resolution (TOF, Orbitrap) or triple quadrupole LC-MS instruments
• Evaluating soft ionization performance for non-target screening and routine quantification
• Illustrating expanded analyte coverage via real-world applications (n-alkanes, PCBs, nitrosamines)

Methodology and used instrumentation

The SICRIT® ion source relies on a dielectric barrier discharge cold plasma generated in a confined capillary, minimizing ion loss and fragmentation. Core components:

• SICRIT® Ion Source with cold plasma for fragment-free ionization
• GC/SPME Module and heated transfer line for gas-tight, loss-free sample transfer
• SICRIT® SC-30 Control Unit for precise plasma and module parameter management
• Vendor-specific MS interfaces to connect to Thermo Fisher, Agilent, SCIEX, Bruker, Waters, Shimadzu and JEOL systems
• Examples of third-party equipment: Agilent 8860 GC, CTC PAL RTC autosampler

Main results and discussion

Soft plasma ionization achieved excellent sensitivity and minimal fragmentation across diverse analyte classes. Key findings:

• n-Alkanes: clear [M]+ molecular ions with accurate molecular weight determination
• PCBs: intact molecular ions with isotopic patterns enabling unambiguous identification
• Nitrosamines: low nanogram-per-milliliter limits of detection using MRM transitions on a triple quadrupole
• Non-target screening: high resolution TOF/Orbitrap data deliver unmatched selectivity for unknowns in complex matrices

Comparative spectra confirm that SICRIT® produces almost no fragmentation versus traditional electron ionization, while covering much of the ionization range of APCI and parts of ESI and EI.

Benefits and practical applications

The GC-SICRIT®-MS workflow delivers:

• Consolidated instrument platform reducing capital and operational costs
• Reduced sample preparation and data integration efforts by avoiding separate GC-MS and LC-MS analyses
• Flexible coupling to meet tasks requiring either targeted quantification (MRM) or comprehensive non-target screening

Applications include pesticide residue quantification, environmental contaminant screening, food safety and forensic toxicology.

Future trends and potential uses

Advances may include integration with GCxGC for enhanced separation, coupling to novel high-resolution MS architectures, and incorporation of AI-driven data analysis for rapid non-target feature identification. Expansion toward semi-volatile and mid-polar biomolecules could further broaden application scope.

Conclusion

The SICRIT® soft plasma GC-MS interface transforms existing LC-MS instruments into dual-mode platforms, combining the strengths of GC and LC-MS. Its high sensitivity, minimal fragmentation and broad ionization range offer streamlined workflows, cost savings and robust performance for both targeted and non-targeted analyses.

References

• NIST Chemistry WebBook, NIST Standard Reference Database Number 69; available at https://webbook.nist.gov/chemistry/