Profiling flavourings in strawberry‐flavoured e‐liquid using headspace‐gas chromatography–mass spectrometry

Abstract

E‐liquids typically contain nicotine and flavourings in a matrix of propylene glycol (PG) and vegetable glycerine (VG). Some nicotine‐free e‐liquids are flavouring only in the aerosol carrier with the option for users to add their own nicotine. It is only the nicotine that is monitored in terms of level, as specified by the manufacturers. Little is known of the toxicological effect for some of the flavourings in the context of vaping as these are only regulated for ingestion and not inhalation. A method was developed to analyse volatile organic compounds (VOCs) evolved when e‐liquids are vaporised based on headspace‐gas chromatography–mass spectrometry (HS‐GC‐MS) for e‐liquids. An in‐house standard was prepared with sample matrix and purchased strawberry flavouring to simulate a simple e‐liquid but with known levels. This standard was then used to optimise the analysis for use with e‐liquid samples but not for full quantification purposes. These were purchased from a range of retailers and with different batches but mainly focussed on strawberry flavour. The results identified three key components indicative of strawberry flavour (ethyl‐3‐methyl butanoate, ethyl 2‐methyl butanoate and ethyl butanoate) and showed considerable variation between both manufacturers and batches. Flavouring VOCs are regulated for ingestion but are not regulated for e‐liquid inhalation, so these could have toxicological implications. In addition, the inconsistency between samples suggests further issues when users add their own nicotine to the e‐liquids as the viscous sample matrix makes homogeneous mixing difficult.

The science behind vaping

“…Holt et al 2 deliver a case report on products containing cannabinoids with a collation of 11 case reports where alarmingly 8/11 individuals reported 'hallucinogenic or dissociativelike effects' while 10/11 cases reported use of 'THC-free' or off-label presence of Δ-9-THC in concentrations ranging from 0.02 to nearly 500 mg/mL. Haworth-Duff et al 3,4 report on two preliminary analyses of e-cigarette aerosols, one focusing on the analysis and characterisation of a strawberry flavour aerosol using headspace-gas chromatography-mass spectrometry, 3 and the other on the analysis of trace metals using inductively coupled plasma-mass spectrometry (ICP-MS), 4 which show promise for future quantitative characterisation of constituents in vape aerosols.…”