Ex vivo detection of recreational consumed nitrous oxide in exhaled breath

The increasing use of recreational nitrous oxide ([Formula: see text]O) in the Netherlands and its link to traffic accidents highlights the need for reliable detection methods for law enforcement. This study focused on ex vivo detection of [Formula: see text]O in exhaled breath and examining its persistence in the human body. Firstly, a low-cost portable infrared based detector was selected and validated to detect [Formula: see text]O in air. Then, the influence of interferents and conditions potentially influencing the analysis were evaluated including relative humidity, ethanol, acetaldehyde and [Formula: see text]. Subsequently, [Formula: see text]O breathing dynamics were evaluated in vitro and ex vivo. Initially, a lung simulator was used to model respiratory mechanics and [Formula: see text]O decay, revealing detectable [Formula: see text]O levels up to 90 min after exposure. In the final part of this study, a controlled single and double dose of [Formula: see text]O gas was administered to 24 volunteers in an operating theatre. The presence of [Formula: see text]O in exhaled breath of the volunteers was analysed using infra red spectroscopy every 12-15 min. Our results show that [Formula: see text]O was detectable in exhaled breath for a minimum of 60 min post-administration and revealed a window of detection to potentially measure [Formula: see text]O for law enforcement and forensic purposes.