Nitrogen analyzer adaptation for use in the presence of halogenated anesthetics

Interposition of activated carbon between a nitrogen analyzer needle valve and gas mixtures containing halothane, methoxyflurane, enflurane, or isoflurane eliminated the interfering effects of these agents, but added sampling delays. Placement of a carbon-filled Swinney adaptor in the sampling line between the needle valve and analyzer also eliminated the interference. Linearity of response (range 0 to 80 per cent N2) and sampling delay (40 msec) were unchanged. The 90 per cent fall time (step change 80 to 0 per cent N2) increased from 35 to 100 msec. This adaptation allows rapid analysis of nitrogen concentrations during general anesthesia.