Method for simultaneous determination of three cooling agents in aerosols by GC–MS

TL;DR

This paper introduces a reliable GC-MS method to measure three cooling agents in aerosols, showing their distribution in gas and particle phases.

Contribution

A validated GC-MS method for simultaneous quantification of three cooling agents in aerosols is developed and tested.

Findings

The method showed excellent linearity, low detection limits, and high accuracy for quantifying cooling agents.

Cooling agents were predominantly found in the particle phase due to aerosol condensation.

Gas-phase proportions of menthol, WS-23, and WS-3 were significantly lower than in the particle phase.

Abstract

A cooling sensation is primarily elicited by cooling agents through activation of cold-sensitive receptors such as TRPM8 and TRPA1. Coolants are widely used as functional additives in various industries including food, personal care, pharmaceuticals, and tobacco. In this study, a gas chromatography–mass spectrometry (GC-MS) method was developed to quantify three representative cooling agents—menthol, WS-3(N-ethyl-2-(isopropyl)-5-methylcyclohexanecarboxamide), and WS-23 (2-Isopropyl-N,2,3-trimethylbutyramide)—in aerosol samples. The test aerosols were generated from laboratory-formulated e-liquids under optimized conditions. Aerosols were obtained from an electronic vaping device manufactured by RELX (China). The results demonstrated that: (1) the analytical method exhibited good linearity (R
2 ≥ 0.9994), with limits of detection (LOD, from 0.137 ng/mL to 0.114 μg/mL), limits of quantification (LOQ, from 0.456 ng/mL to 0.380 μg/mL), relative standard deviations (RSDs, 1.40%–4.15%), and spiked recovery rates (from 91.32% to 113.25%) all meeting the requirements of analytical validation; (2) the cooling agents were detected in both gas and particle phases of the aerosol, with the concentrations in gas-phase being significantly lower than those in the particle phase due to aerosols condensation. Specifically, the gas-phase proportions of menthol, WS-23 and WS-3 ranged from 1.94% to 5.72%, 0.03%–0.08%, and 0.10%–0.18%, respectively. Therefore, the developed GC-MS method satisfies methodological validation criteria and is suitable for application to commercial aerosol samples. It provides a reliable analytical foundation for studying sensory perception of cooling agents under aerosol exposure and offers more precise guidance for their use.

Figures