Detection of trace copper metal at carbon nanotube based electrodes using squarewave anodic stripping voltammetry

We investigate sensitivity and limit of detection (LOD) of trace copper (Cu) metal using pristine carbon nanotube (CNT) and acidified CNT (ACNT) electrodes. Squarewave based anodic stripping voltammetry (SWASV) is used to determine the stripped Cu concentration. Prior to performing the SWASV measurements, its optimal conditions are determined and with that, effects of potential scan rate and Cu⁺² concentration on stripping current are evaluated. The measurements indicate that (1) ACNT electrode shows better results than CNT electrode and (2) stripping is controlled by surface reaction. In the given Cu⁺² concentration range of 25- 150 ppb, peak stripping current has linearity with Cu⁺² concentration. Quantitatively, sensitivity and LOD of Cu in ACNT electrode are 9.36 μA μM^-1 and 3 ppb, while their values are 3.99 μA μM^-1 and 3 ppb with CNT electrode. We evaluate the effect of three different water solutions (deionized water, tap water and river water) on stripping current and the confirm types of water don't affect the sensitivity of Cu. It turns out by optical inspection and cyclic voltammetry that superiority of ACNT electrode to CNT electrode is attributed to exfoliation of CNT bundles and improved interfacial adhesion occurring during oxidation of CNTs.