DC, pulse, AC, and square wave polarographic techniques are electroanalytical methods used to determine the concentration and nature of electroactive species in solutions. DC polarography applies a continuously increasing voltage to generate a sigmoidal current-voltage curve. Pulse polarography applies voltage pulses to eliminate non-faradaic currents and improve detection limits. AC polarography superimposes an AC potential on DC to measure the AC current component. Square wave polarography uses large amplitude square waves to sample current twice per cycle and plot the net current versus voltage. These techniques enable sensitive quantitative analysis down to micromolar and even nanomolar concentration levels.