Ratiometric sensing of CO2 in ionic liquid modified ethyl cellulose matrix

In this study emission-based ratiometric response of ion pair form of 1-hydroxy-3,6,8-pyrenetrisulfonate (HPTS) to gaseous CO2 has been evaluated in ionic liquid (IL) containing ethyl cellulose (EC) matrix. The ionic liquid: 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIMBF4); provided longer storage time and highly stable microenvironment for the HPTS molecule due to the buffering effect. The utilization of ionic liquid in ethyl cellulose matrix resulted with superior spectral characteristics. The excitation spectra of HPTS exhibited an atypical isoemmissive point in modified EC matrix at 418 nm which allows ratiometric processing of the signal intensities. 4-doped sensor films exhibited enhanced linear working range between 0 and 100% pCO2. The signal changes were fully reversible and the shelf life of the EMIMBF4-doped films was extended from 15 to 95 days.