To determine the concentration of lead ions Pb2+ in a drinking water sample using polarography, follow these steps:1. Prepare the sample: Collect a representative drinking water sample from the home in a clean, contamination-free container. Filter the sample to remove any suspended particles or debris.2. Prepare the polarographic cell: Set up a polarographic cell with a dropping mercury electrode DME as the working electrode, a platinum wire as the auxiliary electrode, and a reference electrode e.g., Ag/AgCl or calomel electrode .3. Prepare the supporting electrolyte: Prepare a solution of a supporting electrolyte, such as 0.1 M KCl, which will not interfere with the analysis of lead ions. This will help maintain a constant ionic strength and minimize the effect of any other ions present in the sample.4. Prepare the standard solutions: Prepare a series of standard solutions containing known concentrations of lead ions e.g., 1, 5, 10, 20, and 50 g/L by diluting a stock solution of lead nitrate Pb NO3 2 with the supporting electrolyte.5. Record the polarograms: Add the supporting electrolyte to the polarographic cell and record the polarogram for each standard solution and the drinking water sample. Adjust the potential of the working electrode DME from a negative value to a more positive value, and observe the current response. The current will increase as the potential reaches the reduction potential of Pb2+ ions, forming a characteristic "wave" on the polarogram.6. Calibration curve: Plot the peak current in A of the polarographic waves obtained for the standard solutions against their respective lead concentrations in g/L . The resulting calibration curve should be linear, with a positive slope.7. Determine the concentration of Pb2+ in the sample: Locate the peak current of the polarographic wave for the drinking water sample on the calibration curve. Read the corresponding lead concentration from the curve. This value represents the concentration of lead ions Pb2+ in the drinking water sample.8. Quality control: To ensure the accuracy of the results, perform replicate analyses of the sample and standard solutions, and include a blank supporting electrolyte only in the analysis. Additionally, analyze a certified reference material CRM with a known concentration of lead ions to verify the accuracy of the method.By following these steps, you can successfully determine the concentration of lead ions Pb2+ in a drinking water sample using polarography.