Thiol-functionalized multiwall carbon nanotubes for electrochemical sensing of thallium

An electrochemical sensor is fabricated using indium tin oxide (ITO) electrode loaded with 3-Amino-1,2,4-triazole-5-thiol functionalized multiwall carbon nanotubes (T-MWCNTs) for detection of thallium. The modified MWCNTs were characterized by FTIR spectroscopy, SEM and HRTEM studies. SEM images demonstrated that the width of tubular structure of T-MWCNTs increase considerably after functionalization. The electrochemical response of the prepared sensor is analysed by performing differential pulse anodic stripping voltammetry (DPASV). T-MWCNTs based sensor was found to exhibit good sensitivity and a broad linear range of 10–100 μg L−1 along with a limit of detection (LOD) of 1.29 μg L−1 for Tl(I). The sensor showed good repeatability (RSD of 1.16% and 2.09% for 20 and 50 μg L−1 concentrations of Tl(I) respectively) and retained ~95% of its response even after 15 days, indicating high stability of T-MWCNTs/ITO/glass electrode towards the detection of thallium. The applicability of the prepared sensor was analysed in real industrial water samples with the help of spiking study that was performed using certified Tl(I) solution traceable to National Institute of Standards and Technology (NIST) and demonstrated a recovery > 96%.