Evaluation of gaseous phase nicotine in e-liquid nicotine salts in e-cigarette aerosols
Nicotine is a key component in many e-cigarette formulations and during the vaping process, nicotine exists in both the gaseous phase and aerosol phase. There are two type of vaping techniques- mouth-to lung (MTL) and direct-to-lung (DTL). The mouth-to-lung puffing mimics cigarette smoking and involves holding the aerosol in the user’s mouth before drawing into the lungs providing an enhanced sensory effect compared to DTL. To better understand the nicotine delivery of MTL and the impact on vaping sensation, we have developed a method to evaluate the quantity of gaseous phase nicotine in nicotine salt and free-base nicotine e-cigarette aerosols, mimicking the MTL puffing at body temperature. This was conducted using a modified syringe and denuder tubes heated to body temperature; to determine if quantitative measurements of the sensory effect could be determined experimentally. A testing method using denuder tubes and GC-FID was used to determine the quantity of gaseous phase nicotine in the e-cigarette aerosols. Denuder tubes are coated with oxalic acid to bind any gaseous phase nicotine. After vaping, tubes were cut, extracted, and analyzed via GC—FID for nicotine. The method was characterized and evaluated to determine suitability for this study. Differences in the quantity of gaseous phase nicotine were observed between the freebase used and ratios of nicotine salts.