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Nitrous Oxide – Difficulties in Detection

Written by: Alan Baker 22nd January, 2024

Purpose and Popularity:

In medicine, practitioners widely use nitrous oxide (N2O) as an analgesic and anaesthetic. Additionally, it serves as a bacteriostatic, a non-oxidising propellant in whipped cream, and as a ripening agent for fruit.

You can legally purchase food grade N2O in cartridges and cylinders in many parts of the world. When inhaled in subanaesthetic doses, N2O can induce euphoria, mood changes, altered body awareness, relaxation, and loss of coordination.

Its recreational misuse is prevalent among younger individuals. Furthermore, 22.5% of participants in the 2021 Global Drug Survey admitted to having used N2O at least once.

The glamorisation of N2O misuse on social media, in addition with a perceived low risk, has led to increased abuse among adolescents.

The widespread littering of cartridges and cylinders reflects the growing popularity of N2O for recreational purposes. The media increasingly reports on N2O related impaired driving, highlighting the absence of on-site or laboratory testing to confirm such abuse.

Difficulties in Detection:

Measuring exposure to N2O is challenging due its quick onset and elimination from the body. In healthcare settings, researchers actively measure occupational exposure to N2O in urine, blood, and exhaled air using gas chromatography (GC) with electron capture detection. Moreover, they have confirmed fatal intoxications by analysing post-mortem samples of blood, brain, and lung tissues through GC.

Driving under the influence of nitrous oxide:

Two published reports quantify N2O in the blood of drivers, covering a total of five cases. A paper [1] presents a retrospective study of GC analysis results from blood samples taken in Danish traffic cases suspected of N2O influence over three years, from 2020 to 2022.

Recent intake of N2O was confirmed in 52 out of 62 blood samples from drivers in Eastern Denmark, tested between 2020 and 2022.

The N2O concentrations ranged from 0.1 to 48 mL/L of blood. Concurrent use of other drugs and alcohol that impair driving ability was confirmed in 26 and 3 cases, respectively. This study demonstrates the feasibility of detecting N2O in whole blood samples using HS-GC-MS with minimal sample preparation.