Disposable sensor for electrochemical determination of chloride ions.

This work describes the development of a new, simple and inexpensive method for the determination of chloride ions, by using voltammetric disposable sensors. The sensor includes three screen printed electrodes: a working, an auxiliary (both carbon based paste electrodes), and a pseudo-reference Ag/AgCl paste based electrode. Since the presence of chloride ions in the solution modifies the equilibrium potential of Ag/AgCl electrode, the concentration of this analyte has been determined through the systematic shift of the voltammetric peak potential of a control species such as potassium ferricyanide, potassium ferrocyanide or ferrocenemethanol. These control species can be used in solution or mixed into the carbon paste of the working screen printed electrode. In order to characterize the developed methods, reproducibility, repeatability and detection limit of the sensors were calculated in each case. Reproducibility values below 3% (n=5) were obtained. When ferrocenemethanol was used as control species, the lowest quantity of chloride ions detected was 10.0mM. A comprehensive study of interfering ions was also carried out. These sensors were successfully applied to determine the chloride content in sea water and in a commercial saline solution sample.