The analysis of e‐liquids: A study on chemical diversity and metal content using gas chromatography‐mass spectrometry and inductively coupled plasma‐mass spectrometry

This work aimed to determine the chemical composition of 22 e‐liquids available on the Slovenian market. Four different gas chromatography (GC) sample introduction techniques; headspace‐GC‐mass spectrometry (HS‐GC‐MS), liquid injection‐GC‐MS (LI‐GC‐MS), HS‐solid‐phase microextraction‐GC‐MS (HS‐SPME‐GC‐MS), and direct‐immersion‐SPME‐GC‐MS (DI‐SPME‐GC‐MS) were employed for qualitative analysis. Various experimental parameters were assessed for each GC sample introduction technique to maximize compound identification. Despite e‐liquid packaging reporting a maximum of eight compounds, GC‐MS identified more compounds in most samples, especially in menthol‐flavored (58 identifiable compounds by HS‐SPME‐GC‐MS), followed by nicotine‐containing and fruit‐flavored samples. HS‐SPME‐GC‐MS identified the highest number of compounds, followed by HS‐GC‐MS, DI‐SPME‐GC‐MS, and LI‐GC‐MS. Nicotine quantification in six samples was performed by LI‐GC‐MS with dilution in methanol. Nicotine concentration in samples ranged from 16.5 ± 0.5 to 18.5 ± 0.4 mg/mL, which was below the declared concentration of 20 mg/mL. Additionally, quantitative analysis of metals in e‐liquids was performed by inductively coupled plasma‐MS after microwave‐assisted wet acid digestion. Iron was the most abundant metal, with its content ranging from 0.024 to 0.354 µg/g. Barium, bismuth, copper, and tin were also determined in several e‐liquids.