Protecting Public Health: Robust Method for E-Cigarette Nicotine Analysis

A method to analyze nicotine in e-cigarette aerosols has been developed and validated, ensuring regulatory compliance and public health safety. This robust approach enhances the monitoring of e-cigarette emissions, crucial for consumer protection.

Researchers at Sciensano, Belgium, have developed and validated a robust method for analyzing nicotine in electronic cigarette aerosols, a significant advancement in public health monitoring. This work, led by Maarten Dill, Eric Deconinck, and Sophia Barhdadi, is essential due to the growing popularity of e-cigarettes and the need for effective market surveillance. The European Union's Tobacco Products Directive requires emission studies for e-cigarette products but lacks standardized guidelines for these studies, making this research critical.

Innovative Approach to E-Cigarette Monitoring

To address this gap, the research team employed a commercial vaping device to generate aerosols, which were then collected on Cambridge filter pads and analyzed for nicotine content using Ultra-High-Performance Liquid Chromatography with Diode-Array Detection (UHPLC-DAD). The method's validation was meticulous, demonstrating accuracy and precision with β-expectation tolerance intervals well within the ±20% acceptance limits. This ensures the reliable measurement of nicotine levels, which is crucial for regulatory compliance and public health safety.

Calibrating for Precision and Reliability

The development of this method involved several critical steps, starting with the calibration of puff volumes. The team optimized aerosol generation conditions and rigorously extracted nicotine from the collected aerosols. Cambridge filter pads were chosen for their effectiveness, capturing nearly all generated aerosol mass with recoveries ranging from 98.9% to 101.4%. Various solvents were tested for nicotine extraction, and it was found that methanol, acetonitrile, and ammonium borate buffer had similar extraction capacities after 20 minutes. Ultimately, the ammonium borate buffer was preferred for its compatibility with the mobile phase used in UHPLC-DAD.

Ensuring Consistency Across Variables

Further tests were conducted to confirm the robustness of the method across different puff volumes, durations, and power settings. While significant changes in puff parameters did affect nicotine yields, necessitating re-validation, the method consistently demonstrated reliable results. Additionally, the method showed consistency in nicotine delivery across various commercial e-liquids, with recoveries ranging between 92.79% and 109.72%. This consistency is vital to ensure that e-cigarette products meet their labeled nicotine content, a requirement for consumer safety and regulatory adherence.

Implications for Regulatory Standards

The validated method not only facilitates the quality control of nicotine concentrations in e-cigarette aerosols but also serves as a model for developing similar emission analysis methods for other substances. The research underscores the importance of systematic and validated approaches in public health monitoring, offering a reliable tool for regulatory authorities to ensure the safety and quality of e-cigarette products. Moreover, the method's accuracy profiles indicated that future measurements would have a 95% probability of falling within the bias limits of [−20%, 20%]. The highest mean relative bias was observed at the highest concentration level, and the within-run repeatability and intermediate precision were acceptable, with the highest RSD being less than 5%.

Method Robustness and Stability

The research team also evaluated the method's robustness by varying the puff volume, puff duration, and e-cigarette power settings. They found that the nicotine yields increased significantly when the puff duration was extended, while the puff volume did not significantly affect nicotine transfer but did impact aerosol mass transfer. The study also revealed that modifying puffing parameters led to a decrease in the overall repeatability of the method. Consequently, the method should be re-validated when drastically changing the puff parameters, which is an important limitation.

In addition to assessing the method's robustness, the researchers investigated the stability of the collected analyte on the Cambridge filter pads and the vaped aerosol extract. They found no significant difference in the final nicotine yield whether the filter pads were extracted immediately or after 24 hours. This stability was crucial for the method's applicability in real-world settings, where delays between sample collection and analysis can occur. The researchers also tested the method's applicability with 15 different e-liquids, confirming its reliability in determining both the nicotine concentration in the e-liquids and the consistency of nicotine delivery in the aerosols.

The research has significant implications for the regulation and quality control of e-cigarette products. By providing a validated method for analyzing nicotine in e-cigarette aerosols, regulatory authorities can ensure that these products meet safety and quality standards, protecting public health. The method developed by the Sciensano team offers a comprehensive approach to monitoring e-cigarette emissions, which can be adapted for analyzing other harmful substances in e-cigarette aerosols. This advancement in e-cigarette research highlights the need for continued efforts to develop standardized and validated methods for product analysis, ensuring consumer safety and informed regulatory decisions.