Concentration and Detection Time of Nitrous Oxide in Blood Following Controlled Inhalation.

Recreational use of nitrous oxide (laughing gas, N₂O) is becoming increasingly common and abuse is often seen in relation to driving, posing significant traffic-safety concerns. Only a few studies exist on blood concentrations of N₂O and its detectability over time after use. In this study, 11 volunteers received controlled administration of 50% N₂O for 10 min, after which blood samples were drawn and analyzed for N₂O by headspace-gas chromatography-mass spectrometry (HS-GC-MS). Pharmacokinetic modelling indicated that elimination of N₂O can best be described by a two-compartment model with half-lives of 2.4 and 31 min. Although both the pharmacological effect and intoxication typically disappear within minutes after intake, N₂O remained detectable in blood for an average of 62 min at a cutoff of 0.2 mL/L and 132 min at a cutoff of 0.05 mL/L.