Mercury isles in titanate nanotubes: a new strategy for using mercury electrodes in analytical application

Abstract

This work reports for the first time the use of titanate nanotubes (TiNT) as adsorbent structure for Hg2+ ions and its use in construction of mercury-based electrodes for analytical applications. TiNTs with diameter of around 15 nm and length between 40 and 200 nm were obtained by hydrothermal alkaline synthesis and characterized by FTIR, DRX, and TEM. A carbon paste electrode modified with 15% (w/w) of TiNT was used for spontaneous mercury ions incorporation, by simply immerging in a Hg2+ solution for 120 s. “Mercury isles” were obtained by electrochemical reduction of adsorbed Hg2+ ions. Under the best optimized conditions, the proposed device was evaluated for the determination of Zn2+ ions in pharmaceutical samples. A linear relationship of anodic peak current and Zn2+ ions concentration was observed at a range of 4.0–20 µmol dm−3, with sensitivity of 0.54 μA dm3 μmol−1, limit of detection and limit of quantification of 1.2 µmol dm−3 and 4.0 µmol dm−3, respectively. Satisfactory agreement with a comparative method showed the useful application of the sensor, with the advantage of the Zn preconcentration step at open circuit potential condition. This strategy allows the use of several electrodes at the same time, which characterize this device as a feasible passive sampler.