Sensitive detection of estriol hormone in creek water using a sensor platform based on carbon black and silver nanoparticles

We report the electrochemical detection of estriol using carbon black nanoballs (CNB) decorated with silver nanoparticles (AgNP) as electrode material. Homogeneous, porous films on glassy carbon electrodes (GCE) were obtained, with diameters of 20 - 25 nm for CNB and 5 - 6 nm for AgNP. CNB/AgNP electrodes had increased conductivity and electroactive area in comparison with bare GCE and GCE/CNB, according to cyclic voltammetry and electrochemical impedance spectroscopy. The oxidation potential peak was also down shifted by 93 mV, compared to the bare GC electrode. Differential pulse voltammetry data were obtained in 0.1 mol L-1 PBS (pH 7.0) to detect estriol without the purification step, in the linear range between 0.2 and 3.0 mu mol L-1 with detection and quantification limits of 0.16 and 0.5 mu mol L-1 (0.04 and 0.16 mg L-1), respectively. The sensor was used to detect estriol in a creek water sample with the same performance as in the official methodology based on high performance liquid chromatography.