To identify the presence of nitrate ions NO3- in a given solution using ion-selective electrodes ISEs , follow these steps:1. Prepare the nitrate ion-selective electrode: First, you need a nitrate ion-selective electrode, which is a type of sensor that can selectively measure the concentration of nitrate ions in a solution. The electrode typically consists of a solid-state membrane that selectively interacts with nitrate ions, a reference electrode, and an internal filling solution.2. Calibration: Before using the nitrate ISE, you need to calibrate it. Prepare a series of standard solutions with known concentrations of nitrate ions. Measure the potential voltage of each standard solution using the nitrate ISE and the reference electrode. Plot the measured potentials against the logarithm of the nitrate ion concentrations to create a calibration curve.3. Measure the potential of the unknown solution: After calibrating the electrode, immerse the nitrate ISE and the reference electrode in the unknown solution. Measure the potential voltage between the two electrodes.4. Determine the concentration of nitrate ions: Use the calibration curve to find the concentration of nitrate ions in the unknown solution. Locate the measured potential on the y-axis of the calibration curve, and find the corresponding nitrate ion concentration on the x-axis logarithm of the concentration . Convert the logarithm value back to the actual concentration.Keep in mind that the accuracy of the measurement can be affected by interfering ions, pH, and temperature. It's essential to control these factors during the experiment and consider them when interpreting the results.In summary, ion-selective electrodes can be used to identify the presence of nitrate ions in a solution and determine their concentration. The process involves calibrating the electrode, measuring the potential of the unknown solution, and using a calibration curve to find the nitrate ion concentration.