A Mass-Sensitive Approach for the Detection of Anaesthetic Xenon

Quartz crystal microbalances (QCMs) were utilized for the detection of the noble gas xenon (Xe) by combining them with different recognition layers such as permethylated calixarenes (tetramethyl-tert-butylcalix[4]arene (Cal4Me), hexamethyl-tert-butylcalix[6]arene (Cal6Me)), and polyurethanes, with covalently embedded Cal4OH (Poly4Cal), or Cal6OH (Poly6Cal). A third type of sensitive material is synthesized from polyacrylic acid (PAA) and polyvinyl alcohol (PVA) and utilized as a sensitive coating. The results demonstrate that the Cal4Me layer gives higher response towards Xe, while, by the use of a second uncoated QCM channel, the influence of ambient humidity could be nearly completely compensated by signal subtraction. Moreover, the Cal4Me sensor shows excellent reversibility and rapid response time, providing a potentially reliable way to determine Xe during anaesthesia.