Square wave voltammetry SWV is an electroanalytical technique that can be used to determine the concentration of lead ions in a water sample. The method involves applying a potential waveform to a working electrode, which is immersed in the sample solution, and measuring the resulting current. The potential waveform consists of a series of square waves, with each wave having a forward and reverse potential step. The current response is measured at the end of each potential step, and the difference between the forward and reverse currents is plotted as a function of the applied potential.To determine the concentration of lead ions in a water sample using SWV, follow these steps:1. Prepare the water sample: Collect the water sample and filter it to remove any suspended particles. If necessary, adjust the pH of the sample to ensure that the lead ions are in a suitable oxidation state for the analysis.2. Prepare the electrode: Clean the working electrode usually a glassy carbon or a mercury film electrode to ensure a reproducible surface. This can be done by polishing the electrode with alumina slurry and rinsing it with deionized water, followed by electrochemical cleaning in a suitable electrolyte solution.3. Prepare the supporting electrolyte: Prepare a solution of a suitable supporting electrolyte, such as potassium chloride KCl or sodium acetate CH3COONa . The electrolyte should not react with the lead ions and should provide a stable background current during the analysis.4. Set up the electrochemical cell: Assemble the electrochemical cell, which typically consists of a working electrode, a reference electrode e.g., Ag/AgCl , and a counter electrode e.g., platinum wire . Add the water sample and the supporting electrolyte to the cell.5. Perform the SWV analysis: Set up the square wave voltammetry parameters, such as the initial potential, final potential, step potential, amplitude, and frequency. Apply the potential waveform to the working electrode and record the resulting current response.6. Analyze the data: Plot the difference between the forward and reverse currents as a function of the applied potential. Identify the peak corresponding to the reduction of lead ions Pb2+ to Pb . The peak potential is typically around -0.5 V vs. Ag/AgCl for lead ions.7. Calibration and quantification: Prepare a series of standard solutions containing known concentrations of lead ions in the same supporting electrolyte. Perform SWV analysis on each standard solution and plot the peak current as a function of the lead ion concentration. Use this calibration curve to determine the concentration of lead ions in the water sample based on the peak current observed in the SWV analysis.By following these steps, you can accurately determine the concentration of lead ions in a water sample using square wave voltammetry.