OPTOCHEMICAL HCL AND CL-2 GAS-DETECTION BASED ON TETRAPHENYLPORPHIN DISPERSED IN ETHYLCELLULOSE

To detect sub-ppm levels of HCl gas, spectral changes of tetraphenylpo rphine and derivatives dispersed in ethylcellulose were examined in th e visible region. For free base tetraphenylporphyrin, the absorbance a t 450 nm and 670 nm is sensitive to sub-ppm levels of HCl and also a g ood reversibilty is observed at room temperature. The Soret and Q-band s are insensitive to NH3, Cl-2, NO2 and NO at room temperature. For zi nc tetrabromotetraphenylporphine, the absorbance at 479 nm and 722 nm is sensitive to sub-ppm levels of HCl gas and also good reversibilty i s observed at room temperature.