Determination of anesthetic gases at subnarcotic concentration levels

Anesthetic gases are suspect to be of potential health risk in subnarcotic concentrations at conditions of long term exposure. A workplace control for those people working in the environment of surgery requires a low level monitoring of the volatile anesthetics. In order to evaluate the circumstances of long term exposition, measurements of the individual exposition of the involved personal as well as average air concentrations need to be performed. The most common gases to be monitored include N2O, halothane and isoflurane. For the sensitive off-line analysis in the chemical laboratory sampling is accomplished either with gas sampling bags or by adsorption onto activated charcoal. For trace analysis of the anesthetic gases headspace methodology with displacement and subsequent gas chromatographic determination with electron capture- or mass spectrometric detection is applied. The potential of headspace analysis for the estimation of halothane and its metabolite trifluoroacetic acid from body fluids like blood or urine of exposed individulas is explored. For a continous long time monitoring of workplace air the suitability of a portable infrared monitor based on photoacoustic measurement is tested. For the application of this technique the interferences from desinfectants need to be considered.