Equilibrium studies on colorimetric plastic film sensors for carbon dioxide

The equillibrium responses of three new colorimetric plastic film sensors for CO 2 as a function of % CO 2 and temperature are described. the results fit a model in which there is a 1:1 equllibrium reaction between the depronated form of the dye (present in the film as an ion pair) and CO 2 . The 0-50% and 0-90% response and recovery times of each of these films when exposed to an alternating atmosphere of air and 5% CO 2 are determined and in two cases are typically less than 3 s