E-liquids’ hidden alcohol revealed by GC protocol

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  • Published: Jul 1, 2017
  • Author: Ryan De Vooght-Johnson
  • Channels: Gas Chromatography
thumbnail image: E-liquids’ hidden alcohol revealed by GC protocol

Contents of e-cigarette liquids often not listed in USA

E-cigarettes are increasingly popular, but doubts remain about their safety and the appropriate level of regulation

As e-cigarettes are a relatively new product, appropriate regulations are not in place in many countries. Although the EU has recently introduced a requirement for the ingredients in e-cigarette liquids (also known as vaping liquids, vape juices or e-liquids) to be fully listed, in other countries, such as the USA, no such requirements exist. However, the FDA has recently been granted authority to regulate e-cigarettes in the USA. The basic solvent in these liquids is usually glycerol and/or propylene glycol. However, it seems that high concentrations of ethanol are present in some brands.

The researchers from Richmond used GC with headspace analysis to investigate ethanol levels in 56 varieties, 35 of which had nicotine listed as an ingredient. Four of the liquids contained dokha, a high-nicotine tobacco-based product popular in the Middle East. Only one type of e-liquid had ethanol listed as an ingredient. Apart from nicotine, other listed ingredients included caffeine, artificial flavourings and a wide variety of herbal extracts, including wormwood and blue lotus flower (the latter contains psychoactive alkaloids). Three liquids with no ingredients listed on the label were found to contain the synthetic cannabinoid compound MDMB-FUBINACA, a designer drug linked to a number of deaths.

Ethanol detected by GC in many e-liquids

E-cigarette samples were diluted with deionised water and an n-propanol internal standard was added. A Teledyne Tekmar HT3 headspace sampler with an oven temperature set to 160 °C and a sample platen at 80 °C was used. The sample equilibrium time in the headspace sampler was 3.5 minutes. The gas chromatograph was a Shimadzu GC-2014 instrument, fitted with a flame ionisation detector (FID) and a Restek Rtx-BAC1 column, run isothermally at 50 °C with a 6.85 ml/min flow rate.

Ethanol concentrations were determined by means of a calibration curve constructed from known concentrations of ethanol and the internal standard. The method gave good linearity and was shown to give accurate results down to a concentration of 0.05 mg/ml. No sample carryover was detected, showing that the method was suitable for multiple sample injections.

Ethanol was detected in most of the liquids (53 out of 56), the maximum concentration being 206 mg/ml. The one product where ethanol was declared on the label gave a concentration of 56 mg/ml. High concentrations of ethanol were noted in some nicotine-containing e-liquids and also in some that were nicotine free. Presumably ethanol is used as a suitable solvent for other ingredients, although it may also enhance the flavours present. Although there is a large amount of scientific literature on the health effects of drinking ethanol, there has been little research on long-term exposure to hot ethanol vapour. Work on industrial exposure to ethanol vapour may not be applicable to the somewhat different circumstances of e-cigarette usage.

Study on ethanol in e-liquids raises safety question

The authors have developed a simple and accurate technique for evaluating volatile solvents in e-liquids. The results raise questions as to the possible long-term health implications of ethanol vapour exposure. Other solvents used in e-liquids, such as propylene glycol and glycerol, cannot be assumed not to have some adverse health consequences either, since there is a lack of long-term studies into their effects in e-cigarettes, which may differ from those seen from industrial solvent exposure. Other potentially dangerous ingredients, such as alkaloids and synthetic cannabinoids, are also a cause for concern.

Related Links

Drug Testing and Analysis, Early View paper. Poklis et al. Ethanol concentration in 56 refillable electronic cigarettes liquid formulations determined by headspace gas chromatography with flame ionization detector (HS-GC-FID).

Wikipedia, Electronic cigarette aerosol and e-liquid

Article by Ryan De Vooght-Johnson

The views represented in this article are solely those of the author and do not necessarily represent those of John Wiley and Sons, Ltd.

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