Driving under the influence of nitrous oxide - A retrospective study of HS-GC-MS analysis in whole blood

Since 2020, our lab has received blood samples from traffic cases involving suspicion of driving under the influence of nitrous oxide (N₂O). While N₂O analysis by gas chromatography (GC) has been around for decades, quantitative results in blood from drivers have been only scarcely reported. We present a three-year (2020-2022) retrospective study of N₂O from traffic cases in Eastern Denmark with suspected involvement of N₂O intake. Whole blood samples from traffic cases were analysed for N₂O using headspace-GC-MS. Freshly made calibration curves and additions of xenon gas as an internal standard were used for calculation of N₂O concentrations. Positive samples have been defined as having concentrations greater than 0.1 mL N₂O/L blood. Over a three-year period, we have tested 62 traffic case blood samples for the presence of N₂O. Despite the technical challenges associated with the analysis of N₂O, we have found N₂O in 52 of the samples. Calculated concentrations were in the range 0.1-48 mL N₂O/L blood, which are similar to the few cases previously found in the literature.