Novel amperometric sensor based on mesoporous silica chemically modified with ensal copper complexes for selective and sensitive dopamine determination

Disordered mesoporous silica (DMS), prepared by the sol–gel method, was chemically modified with ensal functional groups. Copper complexes were formed on the surface of the resulting material. A homogeneous mixture of the DMS/(ensal)2Cu with ultra pure graphite (99.99%) was pressed in disk format in order to fabricate a working electrode that displayed an excellent specific electrocatalytic response to dopamine (DA) oxidation. Under optimized conditions, at −20 mV vs. SCE in 0.04 mol L−1 Britton–Robinson buffer (BRB) solution (pH 7.0) containing 200 μmol L−1 of H2O2, a linear response range for dopamine from 5 up to 130 μmol L−1 was obtained with a sensitivity of 21.2 (±0.003) nA L μmol−1 cm−2 and the limit of detection LOD was 0.52 μmol L−1. The sensors presented stable response during successive determinations. The repeatability, evaluated in terms of relative standard deviation of <3% for n = 10 and 10 μmol L−1 dopamine. The response time was 1 s and life time at least 6 months. Finally, the sensor was tested to determine dopamine in the sample, showing a good performance for its determination. The presence of ascorbic acid and NADH did not show any interference in the detection of dopamine on this electrode, even in the same concentration as the dopamine.