Passive sampling and head space analysis for quantitative determination of nitrous oxide exposure.

A new technique has been developed for determining the time-weighted average personal exposure to nitrous oxide gas. Nitrous oxide gas is passively collected on a molecular sieve contained in a glass tube and partially desorbed in a vial until solid-gas equilibrium at 100 degrees C. Next, nitrous oxide concentration in the head space air in the vial is measured with a gas chromatograph equipped with an electron capture detector. This study shows that nitrous oxide concentration in the head space is proportional to both the nitrous oxide concentration in the test atmosphere and the sampling time up to 1600 ppm/hr. The coefficient of variance is less than 10%. The performance of the sampler is not affected by water vapor or carbon dioxide in the atmosphere nor by air currents. The sampler can be stored for 2 weeks at either 4 or 25 degrees C. Because the passive sampler is small and light, it can be used to determine exposure to nitrous oxide during surgical operations.