Characterisation of a Hg(II) ion optrode based on Nafion®-1-(2-thiazolylazo)-2-naphthol composite thin films

Abstract

An optrode for Hg ²⁺ ions based on a Nafion-1-(2-thiazolylazo)-2-naphtol (TAN) composite thin film has been developed. This optrode has a wide linear response range of 1-75 μM (pH 6) of Hg ²⁺ ions with a limit of detection of 0.05 μM (10 μg l ^–1 ), which is sufficiently adequate for many environmental monitoring applications. The reflectance signal response shows a close correlation with the theoretical model derived. The response time of the optrode thin film was within 5-7 min to reach 95% of the final signal, depending on the concentration of Hg ²⁺ ions. The selectivity of optrode to Hg ²⁺ ions in phosphate buffer is good, with Co ²⁺ and Ni ²⁺ ions as the main interferences.