Uniform manganese-loaded titanium dioxide nanotube arrays for accurate detection of trace Cd2+ in water, soil and tea: Enhanced stability and sensitivity

Abstract

The poor stability of the signal obtained on nonuniform substrate, which results from the obvious difference in the size of ablation spots, the uneven distribution of enriched analytes, and the severe matrix effect, seriously affecting the practical application of electrochemical preconcentration supported laser-induced breakdown spectroscopy (ECP-LIBS). Here, self-organizing and ordered manganese loaded titanium dioxide nanotube arrays (Mn-TiO2 NTAs) on a titanium foil was employed as the working electrode to overcome the problem. The Mn-TiO2 NTAs were of equal height, hollow-structured and evenly arranged on the electrode, leading to uniform and shallow ablation spots after Gaussian laser irradiation (proven by MATLAB simulation), which reduced the matrix effect. As a result, a high sensitivity of 13347.7 counts μM−1 and low LOD of 0.01 μM for Cd2+ were achieved. Most importantly, the self-organizing and ordered Mn-TiO2 NTAs electrode exhibited outstanding stability and reproducibility (relative standard deviation, RSD, was less than 5%), while the Mn-TiO2 electrode modified through the drip coating method showed poor stability (RSD was greater than 20%). The proposed method perfectly achieved the anti-interference and accurate detection of Cd2+ in water, soil and tea.