Electroanalytical technique:
An electroanalytical technique is based on the measurement of one or more electrical quantities and their magnitudes could be correlated with the nature, concentration or total amount of the analyte. In most of the cases, the name of the technique is based on electrical quantity measured or the unit of the measured electrical quantity. At least one technique, polarography is named on the basis of a particular type of electrode (dme) used.
- The understanding of electrode potential is of fundamental importance. It is measured with respect to an arbitrarily defined reference electrode, the standard hydrogen electrode whose potential was given zero volts at all temperatures.
- An electrochemical cell can operate to convert chemical energy into electrical energy or vice-versa depending on whether the cell reaction is spontaneous or forced to occur in the non-spontaneous direction. A galvanic cell having two appropriate half-cells operates spontaneously. The emf of a galvanic cell is the difference between the potentials of the two electrodes and the liquid-junction potentials. A quantitative relation between equilibrium potential and activities of the involved substances was given by Nernst. The relationship is called the Nernst equation.
- The various electroanalytical techniques are classified on the basis of the particular electrical variable or variables measured by keeping the other variables constant and the mode of mass transport. On the basis of these considerations the electroanalytical techniques are classified as: potentiometry, voltammetry polarography, amperometry, conductometry, coulometry, and electrogravimetry.