LC–MS/MS analysis of components in smoke from e-cigarettes that use guarana extract as the caffeine source

Currently, e-cigarette products to inhale caffeine (Caf) are commercially available and widely used. Guarana extract (GE) is used as the caffeine source in some e-cigarette products. In this study, an LC–MS/MS analysis of components in the smoke from e-cigarettes with GE was performed. The concentration ranges of Caf and the minor components theophylline (TP), theobromine (TB), and paraxanthine (PX) in e-liquid and cigarette smoke extract (CSE) of five e-cigarette products were determined. The concentration ranges of e-liquid and CSE were 2.17–8.62 mg/mL and 0.17–1.17 µg/puff for Caf, 0.09–37.58 µg/mL and 0.03–11.88 ng/puff for TB, 50.28–185.26 ng/mL and 0.00–0.05 ng/puff for TP, and 0.44–4.09 µg/mL and 0.03–0.20 ng/puff for PX, respectively. By comparing the peak area ratios of e-liquid and CSE, we clarified that the heat degradation of Caf to its related components in GE products was accelerated. Epicatechin, which is another typical component in GE, was determined for CSE, but not for e-liquid.