1 research outputs found
Gold nanoelectrode ensembles for direct trace electroanalysis of iodide
A procedure for the standardization of ensembles of gold nanodisk electrodes (NEE) of 30 nm diameter is presented, which is based on the
analytical comparison between experimental cyclic voltammograms (CV) obtained at the NEEs in diluted solutions of redox probes and CV
patterns obtained by digital simulation. Possible origins of defects sometimes found in NEEs are discussed. Selected NEEs are then employed
for the study of the electrochemical oxidation of iodide in acidic solutions. CV patterns display typical quasi-reversible behavior which involves
associated chemical reactions between adsorbed and solution species. The main CV characteristics at the NEE compare with those observed at
millimeter sized gold disk electrodes (Au-macro), apart a slight shift in E1/2 values and slightly higher peak to peak separation at the NEE. The
detection limit (DL) at NEEs is 0.3 M, which is more than one order of magnitude lower than DL at the Au-macro (4 M). The mechanism
of the electrochemical oxidation of iodide at NEEs is discussed. Finally, NEEs are applied to the direct determination of iodide at micromolar
concentration levels in real samples, namely in some ophthalmic drugs and iodized table salt