Sensitivity:

The above sensitivity for reversible redox processes can be improved to about (5-10)^-7 mol/dm³ if the AC is measured at a particular phase shift with reference to the excitation signal in order to separate the Faradaic and capacitive current. This is the 1st harmonic AC polarography (AC-1, polarography). A measurement of the harmonic of the AC resulting from the nonlinearity of the Faradaic resistance, e.g. 2nd harmonic along with the aid of phase chosen rectification (AC - 2 polarography) decrease the capacitance current contribution therefore increasing the sensitivity and the selectivity of the determination. A market available instrument is equipped to measure both the types of currents.