Immobilization of ruthenium tris-bipyridyl complex for chlorine gas detection

The fluorescence of tris-bipyridyl ruthenium complex (Ru-TRL) is sensitive to changes in chlorine gas concentration through dynamic quenching processes. However, the use of TRL in conjunction with a fibre-optic-based sensing system depends on finding a suitable immobilization medium for use with such a system. Several physical methods of immobilization have been examined, namely, XAD 4, polyvinyl pyrrolidone (PVP) and silicone rubber as suitable matrices, and it has been shown that the use of both PVP and silicone rubber as matrices for TRL allows the design of an optical sensor with rapid response to measure low chlorine gas concentrations. Limits of detection of 0.675 and 1 ppm have been possible using PVP and silicone rubber, respectively, as immobilization matrices under nitrogen atmospheres. Further studies have shown that the limit of detection for Ru-TRL in silicone rubber increased to 5 ppm under an atmosphere of air.