Estimation of nitrous oxide in blood

Abstract
The estimation of nitrous oxide (N20) at trace and analgesic levels in whole blood is described. A micro-ionisation cross section (MICS) detector was used to measure trace levels of N2O (0.69 to 17.88 mumol N20/litre of blood); whilst a thermal conductivity (TC) detector was used to determine levels from 0.17 to 13.34 mmol N20/litre of blood. The coefficient of variation was 1.3% and 3.2% for the TC and MICS detectors respectively. The technique equals the precision of previously described methods but is considerably quicker. It appears to be suitable for use in the measurement of blood levels of N20 in both theatre personnel and patients undergoing anaesthesia.