In situ immobilization of nickel(II) phthalocyanine on mesoporous SiO2/C carbon ceramic matrices prepared by the sol-gel method: Use in the simultaneous voltammetric determination of ascorbic acid and dopamine

Three carbon ceramic materials with different porosities were prepared by the sol-gel method, using HNO3, HF, and HNO3/HF as catalysts and the surface areas (S-BET) of the products were determined as 246, 201, and 356 m(2) g(-1), respectively. The materials were characterized using N-2 sorption isotherms, scanning electron microscopy, and conductivity measurements. The matrices were used as supports for the in situ immobilization of Ni(II) phthalocyanine (NiPc) on their surfaces. XPS was used to determine the Ni/Si atomic ratios of the NiPc-modified materials. Pressed disk electrodes were prepared with the NiPc-modified matrices, and tested as sensors for dopamine. The electrode prepared using nitric acid showed excellent catalytic activity for the simultaneous determination of ascorbic acid (AA) and dopamine (DA), with sensitivities of 53.02 and 104.17 mu A mmol dm(-3), respectively. Good repeatability was achieved, with R.S.D. values of 3.67% (AA) and 3.53% (DA), as well as high stability. (C) 2012 Elsevier Ltd. All rights reserved.