Potentiometric and fiber optic sensors for pH based on an electropolymerized cobalt porphyrin

Potentiometric and fiber optic sensors based on polymer films were prepared by electrodeposition of the ion-carrier monomer cobalt(II) tetrakis (p-hydroxyphenyl)porphyrin, [Co(p-OH)TPP]. Fiber optic sensors were developed by electropolymerization of the porphyrin on the surface of indium(tin) oxide glass slides. The optical sensors were highly selective to pH, presenting minimal interferences from anions. They had a linear response from pH 8 to 12. Potentiometric sensors were prepared from porphyrin films electrodeposited on glassy-carbon disk electrodes. These electrodes gave a near-Nernstian response to pH from pH 2 to 12 with minimal interferences