Comprehensive determination of flavouring additives and nicotine in e-cigarette refill solutions. Part II: Gas-chromatography-mass spectrometry analysis.

Flavouring compounds are an essential part of e-liquid products for cigarettes. In general, they are regarded as safe for ingestion, but they may have unrecognized risks when they are inhaled. In some cases, manufactures do not currently abide by the Tobacco Products Directive (2014/40/EU) and do not declare the detailed contents of e-liquids on their labels. To help evaluate the health impact of flavouring substances, there is a need for comprehensive approaches to determine their concentrations in e-liquids. For this purpose, a GC-EI-MS method was developed and validated for the simultaneous determination of 46 commonly used flavour additives in e-liquids. The proposed method performed well in terms of the key validation parameters: accuracy (84-113%), inter-/intra-day precision: 0.1-10% and 1-11%, respectively, and sensitivity (limit of detection: 3-87ng/mL). The sample preparation step was based on a simple "dilute & shoot" approach. This study is a complementary method to the LC-MS/MS procedure described in Part I. Both approaches are suitable for the comprehensive determination of 88 flavouring compounds and nicotine and can be used as tools for the rapid evaluation of the quality and safety of e-cigarette products.