Mesoporous silica xerogel modified with bridged ionic silsesquioxane used to immobilize copper tetrasulfonated phthalocyanine applied to electrochemical determination of dopamine

Abstract

Silica xerogel was modified with an ionic silsesquioxane containing the cationic 1,4-diazoniabicyclo[2.2.2]octane bridged group and it was used as matrix for immobilization of copper tetrasulfonated phthalocyanine, resulting in Si/Db/CuTsPc material. This material was characterized by ultraviolet-visible and infrared spectroscopy, elemental and thermogravimetric analyses, nitrogen adsorption-desorption isotherms, and scanning electron microscopy. The Si/Db/CuTsPc material was used to develop a carbon paste electrode for dopamine determination. The electrochemical behavior of dopamine was evaluated by cyclic voltammetry and chronoamperometry. The optimal experimental conditions were determined (pH = 4.5 and oxygen atmosphere) using a 0.1 mol L−1 phosphate buffer solution. The carbon paste electrode modified with the Si/Db/CuTsPc material shows a linear response for current intensity with the dopamine concentration in the range of 0.010 to 0.107 mmol L−1. The detection limit was 0.42 μmol L−1, and the sensitivity was 7.15 μA (mmol L−1)−1, making the system promising to be applied as electrochemical sensor for dopamine.