Walaa Haider Elobeid - University of Khartoum, Faculty of Science, Department of Chemistry, Khartoum, Sudan
Abdalla Ahmed Elbashir - University of Khartoum, Faculty of Science, Department of Chemistry, Khartoum, Sudan

An improvement to the performance of the bare pencil graphite electrode (PGE) was made by modifying it utilizing p-amino benzene sulfonic acid (p-ABSA), benzo-18-crown-6 and multi-walled carbon nanotubes (CNTs) to detect lead (II) ions in water samples using differential pulse anodic stripping voltammetric technique. The presence of p-ABSA serves as ionic conductor while the good adsorption ability and electrical conductivity of multi-walled CNTs enhanced the sensitivity through increasing the electrochemical active surface area. Furthermore, using benzo-18-crown-6 as a molecular scavenger improved the selectivity for lead (II) ions. After optimizing the experimental and chemical parameters, the proposed electrode demonstrated linearity toward the lead (II) ions in a concentration range of 15-200 µM, and 0.99852 correlation factor at 5 sec accumulation time. The detection and qualification limits were statistically calculated based on ICH guidelines as 5.72 µM and 17.32 µM, respectively. The sensor demonstrated a very good selectivity over heavy metals for instance Zn (II), Fe (III), Cr (III), Cu (II) and Mn (VI). The developed method was adequately applied for the determination of Pb (II) ions in water samples. The results obtained by the current method were compared to the acquired results utilizing ICP-OES. According to the statistical consideration, the two methods were considered identical.  

Differential pulse anodic stripping voltammetry, Carbon nanotubes, Crown-ether, molecular scavenger