Ion-selective electrodes ISEs are sensors that can selectively measure the concentration of specific ions in a solution. In this case, we want to use a fluoride ion-selective electrode to determine the concentration of fluoride ions in a sample solution. Here's a step-by-step procedure to achieve this:1. Calibration: First, prepare a series of standard fluoride solutions with known concentrations. These solutions will be used to create a calibration curve, which will help in determining the concentration of fluoride ions in the unknown sample. Typically, at least three standard solutions with different concentrations are needed for accurate calibration.2. Assemble the electrode system: Set up the fluoride ion-selective electrode and a reference electrode e.g., Ag/AgCl electrode in a suitable electrochemical cell. Connect the electrodes to a high impedance voltmeter or an ion meter.3. Measure the potential of standard solutions: Immerse the electrodes in the first standard fluoride solution and allow the potential to stabilize. Record the potential in millivolts displayed on the voltmeter or ion meter. Repeat this process for all the standard solutions.4. Create a calibration curve: Plot the measured potentials y-axis against the logarithm of the fluoride ion concentrations x-axis of the standard solutions. Fit a linear regression line to the data points. The slope and intercept of this line will be used to calculate the concentration of fluoride ions in the unknown sample.5. Measure the potential of the unknown sample: Rinse the electrodes with distilled water and immerse them in the unknown sample solution. Allow the potential to stabilize and record the value.6. Determine the concentration of fluoride ions: Using the measured potential of the unknown sample and the calibration curve, calculate the logarithm of the fluoride ion concentration in the sample. Convert the logarithm value to the actual concentration by taking the antilogarithm 10^x .7. Validate the results: To ensure the accuracy of the results, it's a good practice to measure the potential of a known standard solution after analyzing the unknown sample. This will help to confirm the reliability of the calibration curve and the electrode performance.By following these steps, you can successfully use a fluoride ion-selective electrode to identify the concentration of fluoride ions in a sample solution.