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Silica xerogel was modified with an ionic s i l s e s q u i o x a n e c o n t a i n i n g t h e c a t i o n i c 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.

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