Determination of halides using Ag nanoparticles-modified disposable electrodes. A first approach to a wearable sensor for quantification of chloride ions.

This work reports a simple voltammetric method for the determination of chloride, bromide, and iodide ions using screen-printed carbon electrodes modified with silver nanoparticles electrochemically deposited on the working electrode surface. UV/Vis absorption spectroelectrochemistry was used to study the electrodeposition of silver nanoparticles on the working carbon electrode on PET or Gore-Tex® supports, and their subsequent oxidation in the presence of halide ions. The main figures of merit of the developed sensors, such as reproducibility and detection limit, have been calculated. Reproducibility values of 2.22%, 2.83% and 3.23% were obtained for chloride, bromide and iodide determinations, respectively. Additionally, the lowest detected amount of chloride, bromide and iodide ions were 3.0·10-6 M, 5.0·10-6 M and 5.0·10-6 M, respectively. Taking into account the relevance of the determination of chloride ion concentration in sweat, the voltammetric method for the determination of halides has been successfully transferred to a Gore-Tex® support to build a first approach to a wearable sensor that facilitates the quantification of this ion in sweat samples. The Gore-Tex® sensor provides a good reproducibility (RSD = 1.61%).