A disposable screen-printed silver strip sensor for single drop analysis of halide in biological samples

A screen-printed silver strip with three-electrode configuration of Ag-working, Ag-counter and Ag/AgxO reference electrodes was developed for simultaneous determination of chloride, bromide and iodide in aqueous solutions. It was fabricated simply by screen-printing silver ink onto a polypropylene (PP) base. The in-situ prepared Ag/AgxO reference electrode can avoid the leaching interference in chloride detection while using a conventional Ag/AgCl reference electrode. A single drop of analyte (50 μl) is enough to determine iodide, bromide and chloride by measuring the well-separated oxidation peak currents of respective silver halides. The calibration graph was linear from 10 μM to 20 mM for iodide and bromide and 100 μM to 20 mM for chloride and the detection limit (S/N = 3) was 3.05 μM, 2.95 μM and 18.83 μM for iodide, bromide and chloride, respectively. The strip is designed to be disposable and as such manual polishing is not necessary. The proposed sensor is not only simple to manufacture and easy to operate but also fast and precise with little detection volume. It is successfully applied to the determination of halide ions in real samples.