Application of manganese (II) phthalocyanine synthesized in situ in the SiO2/SnO2 mixed oxide matrix for determination of dissolved oxygen by electrochemical techniques

This work describes the in situ immobilization of Mn(II) phthalocyanine (MnPc) in a porous SiO2/SnO2 mixed oxide matrix obtained by the sol gel processing method. The chemically modified matrix SiO2/SnO2/MnPc, possessing an estimated amount of 8 × 10−10 mol cm−2 of MnPc on the surface, was used to prepare an electrode to analyze dissolved oxygen in water by an electrochemical technique. The electrode was prepared by mixing the material with ultrapure graphite and evaluated using differential pulse voltammetry. Dissolved O2 was reduced at −0.31 V with a limit of detection (LOD) equal to 7.0 × 10−4 mmol L−1. A mechanism involving four electrons in O2 reduction was determined by the rotating disk electrode technique.