Throughout this summer I have the pleasure of working with our intern, Colton Myers. The soon-to-be chemistry senior at Juniata College joined Restek for some practical laboratory experience. We wanted him to work on something “cool” and “interesting,” so what better project is there than electronic cigarettes?You do not have to look very hard to find someone “vaping” on an e-cig, so these things are definitely gaining traction. Despite their explosive popularity, we have only been able to scrape up a few published reports. In fact, a fairly exhaustive peer-reviewed literature search only turned up a couple of articles. So… needless to say Colton has now spent the past month working on the analysis of electronic cigarettes. As a starting point, we worked on the analysis of the “e-juice” only (note, this is a teaser for more to come later).
So we developed an analytical method for a quick screening of e-cig solutions. We utilized SOF and our approach was KISS (keep it simple, stupid). The table below contains all the specifics of interest:
As a first pass, we tore open an e-cig; used 10 mL of methylene chloride to extract out the juice; concentrated the extract down to 1 mL; and here is what it looks like when using the above parameters:
Now… the aforementioned approach was a simple, qualitative pass for determining what was in the e-juice. We did not use any surrogate standards; however, this could be easily done in the future. In fact, these results indicated that nicotine was ~35% of the total solution, which is a far cry off from the manufacturer’s claim of 1.8%. This we attributed to our extraction/concentration procedure, but this did not matter to us, because our next approach was to just purchase some e-juice straight up (that’s right, keep up with the lingo) and analyze the raw solution, thereby cutting out any errors associated with extraction/concentration, etc… And here is what we got for a raw (i.e., unprocessed) 1.8% nicotine solution:
So what does all this mean? Well… our method worked well for the rapid analysis of the major electronic cigarette components and our analyte list matches up “fairly” well with what the manufacturer lists on their website. I say fairly because they do not list ethanol, but we clearly found it; and yes, we ran blanks to ensure this was not a contamination issue (hence, how we found water as a “contaminant”). In addition, according to our results this sample is slightly (yes, not orders of magnitude) off from the manufacturer’s claim of 1.8% nicotine in solution. However, our observation is consistent with what Trehy et al. observed in 2011 (“the nicotine content labeling was not accurate with some manufacturers”). Perhaps this is well within the manufacturer’s tolerances or maybe they do not actually test any of this, because as of now not much of the e-cig business is regulated.
Now… you may be asking “why the thick film volatiles column?”…. well I am glad you asked. Remember my teaser from before? See no one actually drinks, bathes in, or injects (I hope) the e-juice. They “vape” it (i.e., draw the solution over an atomizer and inhale the resulting vapor). So honestly, from my point of view I could really care less about what is in the raw e-cigarette solution. I am more interested in what is found in the vapor. So can you take a guess as to what may be found in later parts of this series? Stay tuned…
Trehy, M.L.; Ye, W.; Hadwiger, M.E.; Moore, T.W.; Allgire, J.F.; Woodruff, J.T.; Ahadi, S.S.; Black, J.C.C; Westenberger, B.J. Analysis of electrongic cigarette cartridges, refill solutions, and smoke for nicotine and nicotine related impurities. J. Lig. Chromatogr. Relat. Tech. 2011, 34, 1442-1458.