Copper Porphyrin Immobilized on MCM-41 Surface by Using Aminopropyl as Coupling Agent and Its Use in Electrochemical Oxygen Determination

Copper porphyrin was immobilized inside of MCM-41 pores using two different methods, by direct addition of copper porphyrin into the MCM-41 pores and by using aminopropyl group as coupling and spacing group. In the second method the aminopropyl group was previously bonded to copper porphyrin ring, resulting in material with higher copper porphyrin amount and dispersion. The materials were characterized by Cu elemental analysis using microwave plasma-atomic emission spectroscopy, X-ray diffraction, N 2 adsorption desorption isotherms and ultraviolet and visible spectroscopy. Carbon paste electrode made with material obtained by second method was used, for the first time, as electrochemical sensors for oxygen determination, showing linear response for current intensity for oxygen concentration in the range of 3.05–23.41 mg L −1 . The detection limit was 0.89 mg L −1 and the sensitivity was 3.79 µA L mg −1 . These characteristics make this system very promising to be applied as electrochemical sensor for oxygen determination.