INTRODUCTION: There are over 35 million electronic cigarette users worldwide with the global vapour product market at over £17 billion pounds. 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. 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.