{HEAD ~ Method} and system for detecting one or more gases or gas mixtures and for measuring the concentration of one or more gases or {TAIL ~ gas mixtures} 
{ HEAD ~ Method } and system for detecting one or more gases or gas mixtures and for measuring the concentration of one or more gases or { TAIL ~ gas mixtures }
HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL