To determine the concentration of nitrate ions in environmental samples using cyclic voltammetry (CV), a technique that measures the current response of an electrochemical cell to a varying potential.

1. Electrochemical Workstation (e.g., Potentiostat/Galvanostat)
2. Three-Electrode System:
   1. Working ElectrodeGlassy Carbon Electrode (GCE)
   2. Reference ElectrodeSilver/Silver Chloride (Ag/AgCl)
   3. Counter ElectrodePlatinum Wire or Mesh
3. Electrolyte Solution: 0.1 M PBS Phosphate Buffer Solution (pH 7.0)
4. Nitrate Standard Solutions: Sodium nitrate,Various concentrations (e.g., 1 mM, 5 mM, 10 mM)
5. Environmental Sample: Water sample with potential nitrate contamination
6. Deionized Water
7. Glassware: Beakers, pipettes, and volumetric flasks
8. pH Meter
9. Protective Equipment: Lab coat, gloves, safety glass

Theory

Cyclic voltammetry (CV) is an electrochemical technique used to study the redox behavior of chemical species by sweeping the potential of a working electrode between two set values in a cyclic manner and measuring the resulting current. In CV, the potential (E) of the working electrode is varied linearly over time, and the resulting current (I) is recorded to generate a voltammogram. The typical cyclic voltammetry experiment involves applying a potential E(t)that changes according to the following equation:
E(t)=E₀+νt

Cyclic voltammetry involves applying a voltage to an electrode immersed in an electrolyte solution, and seeing how the system responds. In CV, a linear sweeping voltage is applied to an aqueous solution containing the compound of interest. A linear sweeping voltage is defined by the voltage (or potential) being varied linearly at the speed of the scan rate Figure 1 illustrates the voltage variation. The voltage flips sign and the potential reverses when it reaches a maximum value, becoming the maximum voltage. The potential of the working electrode is swept linearly between two values (the start and end potentials) at a constant rate (scan rate). This sweep can be forward (positive potential) and reverse (negative potential), creating a cyclic waveform.As seen in Figure 1, the changeover occurs at the peak. The procedure can then be carried over again in a cyclical or periodic fashion.