Application Library

INTRODUCTION: There are over 35 million electronic cigarette users worldwide with the global vapour product market at over £17 billion pounds[1]. Although they are widely used, there is limited characterisation of the composition of e-liquids used during vaping. As vaping becomes an increasing trend, regulations are being introduced for electronic cigarettes and e-liquid manufacturers worldwide. The Tobacco Products Directive 2014/14/EU has recently introduced a limited guideline on the manufacturing of e-liquids[2]. These guidelines are more focused on the concentration of nicotine, caffeine, taurine and colourings rather than flavourings and impurities. Although there are labelling requirements in place, there is no current regulation on a comprehensive list of ingredients; the majority of e-liquids only define propylene glycol, vegetable glycerin and nicotine as ingredients. Scion Instruments developed a method for the quick and easy compositional analysis of e-liquids by gas chromatography with mass spectrometry. Along with the vendor listed compounds, various flavour compounds and impurities were identified.

There are over 35 million electronic cigarette users worldwide with the global vapour product market at over £17 billion pounds[1] . Although they are widely used, there is limited characterisation of the composition of e-liquids used during vaping. As vaping becomes an increasing trend, regulations are being introduced for electronic cigarettes and e-liquid manufacturers worldwide. The Tobacco Products Directive 2014/14/EU has recently introduced a limited guideline on the manufacturing of e-liquids[2] . These guidelines are more focused on the concentration of nicotine, caffeine, taurine and colourings rather than flavourings and impurities. Although there are labelling requirements in place, there is no current regulation on a comprehensive list of ingredients; the majority of e-liquids only define propylene glycol, vegetable glycerin and nicotine as ingredients.
Scion Instruments developed a method for the quick and easy compositional analysis of e-liquids by gas chromatography with mass spectrometry. Along with the vendor listed compounds, various flavour compounds and impurities were identified.

Helium is one of the most common and lightest elements in the universe. The boiling point of helium is closer to absolute zero than any other element. When using helium consideration is rarely given to the fact that it is a non reusable element, meaning the world’s resources of helium are being depleted. Due to the limited availability and the increased sales prices of helium, alternative for helium must be implemented. The importance of carrier gas selection has been a discussion point amongst users of gas chromatography for many years. To serve as a carrier gas in gas chromatography, the gases must be available in sufficient purity and inertness. There are three gases that are commonly used as a carrier gas: nitrogen, helium and hydrogen. The efficiency comparison between these gases is given by the Van Deemter curve which relates the efficiency with carrier gas velocity through the column (speed). Figure 1 shows the Van Deemter curve for nitrogen, helium and hydrogen.
The most efficient gas is hydrogen, followed by helium and nitrogen. Even though the optimum plate height for the three gases are almost identical, helium and nitrogen are behind with respect to analysis time. When viewing the Van Deemter curve, nitrogen has a narrow optimum, with both helium and hydrogen having wider optimums, meaning they may be used at higher velocities with only little sacrifice in separation efficiency. Hydrogen is considered the optimal choice, combining high efficiency separations with short analysis times. However, hydrogen has a safety risk with a 4% concentration in air will lead to explosions.
To date, the worldwide carrier gas of choice has been the second most efficient gas; helium. However, with the rising cost and apparent shortage, the use of alternative carrier gases has increased over time.