Normal Pulse Polarography (NPP):

In this technique, the potential is altered by using square wave potential pulses and is applied only briefly for about 50 ms before each current measurement. The data obtained have the same shape as LSV and the sensitivity is increased. The dropping mercury electrode is held at the initial potential until there are only about 60 ms left in the life time of the drop. Therefore extremely little electrolysis and depletion occurs. During the last 15 ms, before the expiration of the pulse time, the current is measured. Each new drop is stepped upto a greater potential and is measured after about a 40 ms delay, a sensitivity improvement of approximately three times is observed.