GC coupling to LC MS instruments

Significance of the Topic

Mass spectrometry (MS) is a cornerstone of modern analytical chemistry, but different ionization techniques and chromatographic methods often require separate instruments. The SICRIT® (Soft Ionization by Chemical Reaction In Transfer) technology bridges gas chromatography (GC) and liquid chromatography (LC) mass spectrometry worlds into a unified, flexible, and vendor-agnostic solution. By enabling direct, soft ionization of diverse sample types with minimal preparation, SICRIT® expands the range of detectable analytes, enhances sensitivity, and simplifies workflow for routine and advanced analyses.

Purpose and Study Overview

This whitepaper presents the design, capabilities, and performance of the SICRIT® ionization source when coupled to GC and LC-MS instruments. Key objectives include:

• Demonstrate SICRIT® principles and ionization mechanisms.
• Show coupling flexibility with major MS vendors.
• Validate performance in routine pesticide, nitrosamine, and halogenated compound screens.
• Explore advanced applications in high-resolution MS for non-target screening and hydrocarbon elucidation.

Methodology and Instrumentation

The SICRIT® source features a patented flow-through geometry mounted directly on the atmospheric pressure MS inlet. It generates three simultaneous ionization pathways (ESI-like hydronium clusters, APCI-like proton transfer, and PI-like UV photoionization) within a confined plasma chamber. No additional gases or consumables are required.

• Gas Chromatographs: Agilent 7890, 8860, UltraTrace; Varian GC.
• Mass Analyzers: SCIEX Triple Quad (6500 Q-Trap, Ultivo QQQ), SCIEX TripleTOF 4600, SCIEX X500R QTOF, Thermo Orbitrap LTQ XL.
• Carrier Gases: Helium or Nitrogen; standard GC columns (DB-5MS).
• Acquisition Modes: Multiple Reaction Monitoring (MRM), full MS, Data-Dependent Acquisition (DDA).

Key Results and Discussion

• Routine Pesticide Analysis: Achieved signal-to-noise ratios exceeding conventional GC-APCI in 1 pg on-column tests for over 30 pesticide analytes, with robust peak shapes and soft ionization yielding intact molecular ions.
• Nitrosamine Screening: Detected six EPA 521 nitrosamines and the active drug ingredient valsartan at low-fg levels, demonstrating 30× greater sensitivity than LC-APCI on the same instrument.
• Halogenated Pesticides and PCBs: Successfully ionized and quantified perchlorinated pesticides in negative mode and polychlorinated biphenyls in positive mode, achieving detection limits below 5 pg on-column.
• High-Resolution Hydrocarbon Analysis: In GC-Orbitrap runs, SICRIT® enabled molecular adduct detection of n-alkanes (C8–C20) with minimal fragmentation. Calibration curves showed linearity across µg·mL⁻¹ levels for environmental and food analytics.
• Non-Target Screening: By combining GC-SICRIT-MS with an LC-MS spectral database and DDA acquisition at 10 Hz, unknown pesticide components were automatically identified via retention time, accurate mass, and MS/MS spectra.

Benefits and Practical Applications

The SICRIT® GC-MS coupling delivers five major advantages:

1. Unified Ionization: Covers ESI, APCI, and EI analyte classes in a single source.
2. Soft Ionization: Preserves molecular ions for easier identification and structural elucidation.
3. Broad Sample Compatibility: Direct ambient analysis of solids, liquids, and gases without prep.
4. Flexible Vendor Coupling: Interfaces seamlessly to Agilent, SCIEX, Thermo, Waters, Bruker, and Shimadzu MS systems.
5. Advanced Acquisition: Supports MRM, SWATH, and DDA workflows with high-resolution detectors.

Future Trends and Potential Applications

Ongoing developments with SICRIT® may include integration with supercritical fluid chromatography (SFC), laser ablation imaging, and expanded tandem MS libraries for comprehensive non-target screening. The soft ionization principle also shows promise for emerging fields such as metabolomics, lipidomics, and on-site environmental monitoring.

Conclusion

SICRIT® technology transforms MS workflows by unifying GC and LC coupling into one flexible, soft ionization platform. It elevates sensitivity, broadens analyte coverage, and streamlines both targeted and non-target analyses across routine quality control and advanced research. Vendor-independence and minimal consumable needs make SICRIT® a cost-effective tool for laboratories seeking to maximize MS performance.

Reference

• Wolf, J.-C.; "GC coupling to LC-MS instruments" Whitepaper, Plasmion GmbH, May 5, 2020.