Analysis of vaporized caffeine in smoke from e-cigarettes using liquid chromatography–tandem mass spectrometry and clarification of minor components

• Published in: Forensic toxicology Vol. 41; no. 1; pp. 135 - 141
• Main Authors: Takada, Makoto, Saruwatari, Suzuna, Yanagita, Yutaro, Mutoh, Junpei, Harada, Hajime, Kishikawa, Naoya, Kitahara, Takashi, Kuroda, Naotaka, Wada, Mitsuhiro
• Format: Journal Article
• Language: English
• Published: Singapore Springer Nature Singapore 2023
• Subjects: Caffeine - analysis; Chromatography, Liquid - methods; Electronic Nicotine Delivery Systems; Forensic Medicine; Forensic Science; Medical Law; Medicinal Chemistry; Medicine; Medicine & Public Health; Nicotiana - chemistry; Pharmacology/Toxicology; Short Communication; Tandem Mass Spectrometry - methods; Minor components; Vaporized caffeine; E-cigarette; Liquid chromatography–tandem mass spectrometry
• ISSN: 1860-8965; 1860-8973
• DOI: 10.1007/s11419-022-00636-8

Purpose
Electronic cigarettes (e-cigarettes) are used widely, and e-cigarettes containing caffeine (Caf) have recently become commercially available. However, no risk evaluation of these Caf-containing products has been performed to date. Such an evaluation requires a sensitive analytical method for quantifying Caf in smoke from e-cigarettes. The aim of this study was to establish a liquid chromatography–tandem mass spectrometry (LC–MS/MS) method for quantifying vaporized Caf from commercially available e-cigarettes, and to determine minor components related to Caf in cigarette smoke extract (CSE).
Methods
A sampling system for Caf using a suction pump was designed and sampling conditions were optimized.
Results
The optimized LC–MS/MS conditions allowed the sensitive determination of Caf in smoke with a limit of detection of 0.03 ng/mL at a signal-to-noise ratio of 3. The method was applied to CSEs from five e-cigarette products and the concentration of Caf ranged from 0.894 ± 0.090 to 3.32 ± 0.14 μg/mL smoke (
n
 = 3). Additionally, minor components related to Caf, such as theobromine, theophylline, and paraxanthine, were detected in CSE and in e-liquid at very low concentrations, indicating that they were impurities in e-liquid and vaporized along with Caf.
Conclusion
This is the first report to determine the concentration of vaporized Caf using an LC–MS/MS method and to clarify several minor components in smoke from e-cigarettes.