Using GCMS to Determine the 2,3-Butanedione, 2,3-Pentanedione, and Acetoin Content in E-liquid

Importance of the Topic

Flavor compounds like 2,3-butanedione, 2,3-pentanedione and acetoin are widely used in e-liquids but can pose health risks when present at high levels. Regulatory bodies are starting to set strict limits on these diketones, driving the need for reliable analytical methods. A robust GC-MS approach is critical for routine monitoring to ensure consumer safety and regulatory compliance.

Objectives and Study Overview

The study aimed to develop and validate a simple, sensitive and repeatable method using the Shimadzu GCMS-QP2020 NX to quantify 2,3-butanedione, 2,3-pentanedione and acetoin in e-liquid samples. Key goals included establishing calibration linearity, detection limits, repeatability and recovery performance under conditions aligned with draft safety specifications for e-liquids in China.

Methodology

A one-gram aliquot of e-liquid was diluted to 10 mL with ethanol, vortexed at 2 000 rpm for 5 minutes, and filtered prior to analysis. Calibration standards (0.2–2.0 mg/L) were prepared in a propylene glycol/glycerin (80/20) matrix. Quantitation was performed by single-ion monitoring (SIM) of specific m/z values for each compound.

Used Instrumentation

• GC-MS System: Shimadzu GCMS-QP2020 NX
• Column: SH-Rxi-624Sil MS, 60 m × 0.32 mm × 1.8 µm
• Carrier Gas: Helium at constant linear velocity 25.8 cm/s
• Injection: Split mode (20:1), injector at 240 °C
• Column Oven: 60 °C (2 min) → 10 °C/min to 120 °C (2 min) → 25 °C/min to 240 °C (12 min)
• Ion Source: EI, interface 250 °C, source 200 °C
• Data Acquisition: SIM targeting ions 86/43 for 2,3-butanedione; 100/57 for 2,3-pentanedione; 88/46 for acetoin

Main Results and Discussion

Calibration curves for all targets showed excellent linearity (R²>0.9985) over 0.2–2.0 mg/L. Limits of detection ranged from 0.05 to 1.27 mg/kg, and quantitation limits from 0.17 to 4.25 mg/kg. Instrument repeatability tests at 0.2 mg/L yielded RSDs below 4.0 % for all analytes. Recovery experiments on spiked samples (6 mg/kg) demonstrated recoveries between 75.8 % and 112.5 %, confirming the method’s accuracy in real matrices.

Benefits and Practical Applications

• High sensitivity and low detection limits meet or exceed proposed regulatory thresholds.
• Simple sample preparation enables rapid routine testing.
• Strong repeatability and recovery assure reliable quality control in e-liquid manufacturing and regulatory laboratories.

Future Trends and Opportunities

As regulations expand to cover additional contaminants such as phthalates, multi-residue GC-MS/MS protocols may become standard. Coupling headspace or solid-phase microextraction techniques could further reduce matrix effects and streamline workflows. Advanced data processing and library matching will facilitate broader screening for unknown flavoring agents and impurities.

Conclusion

The developed GCMS-QP2020 NX method provides a robust, sensitive and reproducible approach for quantifying key diketone flavorings in e-liquids. Its performance characteristics support compliance monitoring under emerging safety specifications and can be readily adopted in quality assurance and regulatory settings.