Normal-pulse polarography polarogram

Differential pulse polarography also produces an ambiguous record for this kind of situation, as shown in Figure 7.3.18c. A peak is seen only for the Cd " reduction, because the trace covers potentials only on the negative side of the Fe wave. We note again that the differential pulse polarogram approximates the derivative of the normal pulse record hence distinct peaks will not be seen in DPV (or in SWV) unless distinct waves appear in NPV. 

---