Attenuated total reflectance – Fourier transform infrared (ATR-FTIR) spectroscopy analysis for O-H, C-H and C-O functional group in major carrier solvents of raw e-cigarette liquids (PG and VG)

Abstract

Electronic cigarette (EC) is a battery powered device capable to convert liquid into vapour was invented as an alternative to conventional smoker's device. The liquid (e-liquid) in EC commonly contains carrier solvents, flavourings, and nicotine. The main carrier solvents such as propylene glycol (PG) and vegetable glycerine (VG) are known as the primary ingredient in the e-liquid. This study focused on the functional group for the main ingredient of e-liquids, PG, and VG. To achieve the objective of the study, Attenuated Total Reflectance - Fourier Transform Infrared (ATR-FTIR) spectroscopy was used. The fitting process for PG and VG infrared spectra was performed using Origin 9 software. The analysis revealed that PG and VG mainly contained with O-H, C-H, and C-O groups, and its FTIR signal appeared at 3302 cm-1, 3268 cm-1, 2877 cm-1,1036 cm-1, and 1028 cm-1 of wavenumber, respectively. In this case, the hydroxyl or free radical compounds, O-H, C-H, and C-O, could contribute a great potential of harm to human health. In this context, O-H can lead to multiple diseases such as respiratory disease and cardiovascular disease. In addition, C-H in vapour form can cause damage to the kidney or liver organ. In conclusion, all functional groups could be contributing to hazardous and toxicity effect towards human body system. Therefore, exceeding inhalation above the limitations limit recommended of these chemical compounds in PG and VG subsequently will affect the e-cigarettes smokers' health.