Effect of Temperature and Some Common Metals on the Stability of Volatile Anaesthetic-Entonox Mixtures

Abstract

Thermal stability of pressurised ready-to-use volatile liquid anaesthetic mixtures (halothane, isoflurane and enflurane) in Entonox (commercially available premixed 50% N<inf>2</inf>O, 50% O<inf>2</inf> mixture) were investigated at temperatures of 20, 258, 400, 503 and 602°C on glass, stainless steel, copper and aluminium by gas chromatography and GC-MS. It was found that most of the decomposition products formed were halogenated compounds and the observed thermal stabilities in glass, stainless steel and copper allowed a thermal treatment up to 250°C without any decomposition problem. Aluminium was found to be the most effective metal at causing decomposition of the anaesthetic mixtures even at lower temperatures.