QUALITATIVE ANALYSIS OF E-CIGARETTE LIQUIDS USING GAS CHROMATOGRAPHY / MASS SPECTROMETRY

Significance of the topic

E-cigarettes have become widespread consumer products. Analysis of their liquids is essential to understand major components (propylene glycol, glycerin, nicotine) and to screen for minor or trace constituents that may pose health risks. Regulatory developments in the EU and elsewhere increase the demand for robust qualitative screening methods to ensure product safety and compliance.

Study objectives and overview

This application brief demonstrates how a benchtop GC/MS system equipped with full-scan electron impact (EI) detection can be used for the tentative identification of both major and minor constituents in e-cigarette liquids. The approach relies on library searching of acquired mass spectra against the NIST14 EI spectral database.

Methods and instrumentation used

Samples of commercial e-cigarette liquids (mint and “Tutti Frutti” flavors) were diluted to 1% (w/v) in dichloromethane. Both split (50:1 and 5:1) and splitless injections (1 µL) were performed to target abundant and trace components. Chromatographic separation was carried out on a 30 m × 0.32 mm ID DB-624 capillary column with helium in constant pressure mode. The oven program ramped from 50 °C to 240 °C. Mass spectra were acquired from m/z 30–300 using a single quadrupole MS in EI mode. Data processing and library searches employed MassHunter Qual and Unknowns Analysis software.

Used instrumentation

• Agilent 7650A Auto-Liquid Sampler
• Agilent 7820A Gas Chromatograph with EPC split/splitless inlet
• Agilent 5977E Single Quadrupole Mass Spectrometer with inert ion source
• DB-624 Capillary Column, 30 m × 0.32 mm ID, 1.8 µm film thickness
• MassHunter Qualitative and Unknowns Analysis Software

Key results and discussion

Full-scan total ion chromatograms (TICs) of mint and “Tutti Frutti” liquids revealed propylene glycol, glycerin and nicotine as dominant peaks. Splitless injections increased sensitivity, enabling tentative identification of minor flavoring esters. Spiking experiments with potentially harmful compounds (diacetyl, acetylpropionyl, acetoin, diethylene glycol, ethylene glycol) at low concentrations (0.01–0.1% v/v) confirmed system sensitivity and library match capability (scores >900/1000). Deconvolution using Unknowns Analysis resolved co-eluting constituents, uncovering five components in a single peak cluster.

Benefits and practical applications

• Rapid qualitative screening of e-cigarette liquids for quality control and regulatory compliance.
• High sensitivity for trace contaminants and harmful by-products.
• Automated deconvolution to identify overlapping peaks in complex matrices.
• Flexible method adaptable to varying nicotine concentrations and flavor profiles.

Future trends and potential uses

Advances in high-resolution MS and multidimensional GC may further enhance screening of novel additives and thermal degradation products. Integration with predictive toxicology databases could prioritize compounds of concern. Automation in sample preparation and data processing will accelerate large-scale monitoring of e-liquid formulations across manufacturers and regions.

Conclusion

The Agilent 5977E benchtop GC/MS coupled with MassHunter software provides a powerful platform for qualitative analysis of e-cigarette liquids. It achieves efficient separation, sensitive detection of major and minor constituents, and automated library-based identification—even for co-eluting components. This workflow supports quality assurance, consumer safety and regulatory requirements in an evolving market.

References

• Agilent Technologies. Qualitative Analysis of E-Cigarette Liquids Using GC/MS. Application Note 5991-6412EN, October 2015.
• NIST Mass Spectral Library (NIST14, Electron Impact).