Lead is a carcinogenic and neurotoxic heavy metal that it is associated with several health issues at humans even at ultra-trace amounts like neuropathy, liver damage, hallucination, seizures, tremor and coma. In this respect, developing a sensitive, rapid, selective, economic and simple analytical method for its determination is of great importance. As a consequence, in this research, a highly sensitive electrochemical sensor was developed for the square wave anodic stripping voltammetric determination of Pb2+ at ultra-trace levels. A Glassy carbon electrode was modified with an in-situ electroplated bismuth film and the nanocomposite of a recently synthesized melamine based covalent organic framework (schiff base network1 (SNW1)) and Fe3O4 nanoparticles (Fe3O4@SNW1). The obtained results exhibit clearly that combination of Fe3O4@SNW1 and in-situ electroplated bismuth film enhances the sensitivity of the modified electrode towards Pb2+ remarkably. A Plackett-Burman design was implemented for screening experimental factors to specify the significant variables influencing the sensitivity of the electroanalytical method. Afterward, the effective factors were optimized using Box-Behnken design (BBD). Under optimized conditions, the proposed electrode showed a linear response towards Pb2+ in the concentration range of 0.003-0.3 µmol L-1 with the detection limit of 0.95 nmol L-1. The selectivity of the fabricated electrode towards different ionic species were checked out and no serious interference was observed. At the end, the application of the designed sensor in the determination of Pb2+ at 10 different edible specimens were investigated and the obtained recovery values were in the range of (95.56-106.64%) indicating the successful performance of the designed sensor.
