Using GCMS to Determine the Phthalate Content in E-liquid

Importance of the Topic

E-liquids can contain phthalates introduced during production and packaging. These compounds may act as endocrine disruptors, posing health risks. Quantifying phthalate levels in e-liquids is essential to ensure product safety and regulatory compliance.

Objectives and Study Overview

This study aimed to develop and validate a GC-MS method using the Shimadzu GCMS-QP2020 NX for determining 18 phthalates in various e-liquids, following national standard GB 5009.271-2016. Key goals were to assess linearity, sensitivity, repeatability and real sample performance.

Methodology

Sample preparation involved the following steps:

1. Weigh 1.0 g of e-liquid and add 2 mL distilled water.
2. Vortex mix and perform ultrasonic extraction with 10 mL n-hexane.
3. Centrifuge and collect the organic layer.
4. Inject 1 µL of the extract into the GC-MS system.

Instrument Used

• Gas chromatograph mass spectrometer: Shimadzu GCMS-QP2020 NX
• Column: SH-I-5Sil MS (30 m × 0.25 mm × 0.25 µm)
• Carrier gas: helium, constant flow at 1 mL/min
• Injection mode: splitless at 260 °C
• Ionization: EI source at 230 °C, interface at 280 °C
• Temperature program: 60 °C (1 min) → 220 °C at 20 °C/min → 250 °C at 5 °C/min → 290 °C at 20 °C/min
• Detection: selected ion monitoring

Main Results and Discussion

• Linearity: All 18 phthalates showed correlation coefficients above 0.998 over 0.02 to 1.00 µg/mL.
• Limits of detection ranged from 0.042 to 18.072 µg/L.
• Repeatability: Six injections of 0.10 µg/mL standard yielded RSDs below 10 % for all compounds.
• Real sample analysis of three flavored e-liquids demonstrated phthalate concentrations below regulatory limits, with recoveries between 67 and 118 % for spiked samples.

Benefits and Practical Applications

The validated method enables reliable monitoring of phthalate contamination in e-liquids, supporting quality control laboratories and regulatory agencies. It offers high sensitivity, robust repeatability, and straightforward sample preparation.

Future Trends and Possibilities

Ongoing regulatory developments are expected to expand the list of restricted impurities in e-liquids. The method could be adapted to screen additional volatile and semi-volatile contaminants. Integration with high-resolution mass spectrometry may further enhance specificity and allow non-targeted screening.

Conclusion

A GC-MS method using the Shimadzu GCMS-QP2020 NX was successfully established for quantifying 18 phthalates in e-liquids. The procedure meets national standards for sensitivity and precision, providing a reliable tool for safety assessments.

References

• National Food Safety Standards GB 5009.271-2016 Determination of Phthalates in Foods
• Shimadzu Application News 03-GCMS-407-EN Phthalate Analysis in E-liquid, First Edition: Mar. 2022