Multi-walled carbon nanotubes functionalized with bathocuproinedisulfonic acid: analytical applications for the...

This work reports the successful non-covalent functionalization of multi-walled carbon nanotubes (MWCNTs) with bathocuproinedisulfonic acid (BCS) and the analytical application of the resulting dispersion (MWCNTs-BCS) to develop an electrochemical sensor for Cu(II) quantification. The sensor was obtained by casting glassy carbon electrodes (GCEs) with MWCNTs-BCS. The sensing mechanism was based on the open circuit preconcentration of Cu(II) at the electrode surface by complexation of Cu(II) through the phenanthroline ring nitrogen of the BCS that supports the MWCNTs, the reduction of the preconcentrated Cu(II), and final differential pulse voltammetry-anodic stripping in 0.020 M acetate buffer, pH 5.00. The sensitivity of the sensor was (2.73 ± 0.08) μA μM^-1, with a linear range between 5.0 × 10^-7 M and 6.0 × 10^-6 M, a detection limit of 0.15 μM (9.5 μg L^-1), and reproducibility of 6.2% using the same dispersion and 7.1% using three different MWCNTs-BCS dispersions. The quantification of Cu(II) was highly selective even in the presence of As³⁺, Cr³⁺, Cd²⁺, Ni²⁺, Pb²⁺, Co²⁺, Zn²⁺, Fe²⁺, Hg²⁺, Rh, Ir, and Ru. The proposed sensor was successfully used for quantifying Cu(II) in tap water. Graphical abstract.