To determine the concentration of lead ions in a sample using an ion-selective electrode ISE , follow these steps:1. Preparation of equipment and solutions: a. Calibrate the lead ion-selective electrode Pb2+-ISE using standard solutions of known lead concentrations. b. Prepare a series of standard solutions with different concentrations of lead ions e.g., 0.1, 1, 10, and 100 ppm using a lead nitrate or lead acetate salt. c. Prepare a reference electrode, such as a silver/silver chloride Ag/AgCl electrode. d. Assemble the ion-selective electrode system, which includes the Pb2+-ISE, reference electrode, and a pH meter or voltmeter.2. Calibration: a. Immerse the Pb2+-ISE and reference electrode in the first standard solution. b. Allow the system to equilibrate, and then record the potential voltage reading. c. Repeat this process for each standard solution, creating a calibration curve by plotting the potential readings against the logarithm of the lead ion concentrations.3. Sample analysis: a. Collect the sample to be analyzed and filter it if necessary to remove any suspended particles. b. Immerse the Pb2+-ISE and reference electrode in the sample. c. Allow the system to equilibrate, and then record the potential reading. d. Compare the potential reading of the sample to the calibration curve to determine the concentration of lead ions in the sample.4. Data analysis: a. Use the Nernst equation to calculate the concentration of lead ions in the sample. The Nernst equation is as follows: E = E0 + 2.303 * RT/nF * log10 [Pb2+] where E is the measured potential, E0 is the standard potential, R is the gas constant, T is the temperature in Kelvin, n is the number of electrons transferred 2 for Pb2+ , F is the Faraday constant, and [Pb2+] is the concentration of lead ions. b. Solve the Nernst equation for [Pb2+] using the potential reading from the sample and the calibration curve data.5. Quality control: a. Analyze a blank sample e.g., deionized water and a standard reference material with a known lead concentration to ensure the accuracy and precision of the method.By following these steps, you can determine the concentration of lead ions in a sample using an ion-selective electrode.