The spectrophotometric properties of porphyrins are altered upon interaction with nucleic acids, proteins, and amino acids. TPPS immobilized as a monolayer onto a cellulose film exhibits an absorbance peak in the Soret region. The interaction of the porphyrin with the follwing amino acids arginine, glycine, histidine and serine induces blue shifts in the Soret that enables us to quantify and identify these amino acids in the nM scale. The interaction of PCP with the following porphyrins and metaloporphyrins TPPS, Zn-TPPS, TPPS1, C1TPP, C4TPP, Cu-C4TPP in solution induces a red shift in the Soret spectrum that enables us to quantify PCP in concentrations less than the MCL recommended by EPA. The interaction of the TPPS1 immobilized as a monolayer on a Kimwipe(r) tissue with PCP induces a red shift in the Soret spectrum that enables us to detect PCP as low as 0.5ppb. The Photocatalytic degradation of PCP by the above porphyrins in solution and the immobilized TPPSCl as catalysts in pH7 buffer was achieved using fluorescence light. It is believed that singlet oxygen 1O2 is the major oxidant species that was photosensitized, and accomplish the mineralization of PCP to CO2 and HCl.