Cathodic stripping voltammetric determination of iodide using disposable sensors

The World Health Organization considers iodide deficiency diseases (IDD) to be a public health problem. The main indicator to access IDD is urinary iodide, since approximately 90% of the ingested iodide uses this clearance path, with urine being a preferable target for the analysis. In this work, two screen-printed carbon electrode (SPCE) based sensors were developed to determine iodide by using only a single drop of sample. A first approach based on a SPCE proves to selectively determine iodide through the control of the cathodic stripping voltammetric (CSV) parameters. However, this strategy exhibits a gap in determining trace iodide concentrations, which is improved by modifying the working electrode surface with a chitosan coating. The performance of this new CS/SPCE-based sensor was compared with that of the previous SPCE-based sensor, showing improved iodide determination sensitivity. A limit of detection of 1.0 × 10^-8 M and a linear analysis range of 0.15-500 µM were achieved with this sensor. The application of both sensors to real-life samples found values close to those determined by the standard Sandell-Kolthoff spectrophotometric method, proving them to be powerful analytical tools for iodide determination in different kinds of samples, including biological matrices.