Method of standard addition:

The polarogram of the unknown is first recorded and then a known amount of standard solution of the same ion is added and a second polarogram is taken. The calculations are made as below.

If i _di is the wave height the first polarogram of unknown solution of volume V and of 1concentration, c_u and i_d2  is the wave height of second polarogram after adding v cm³ of standard solution of concentration cs, then according to Ilkovic equation:

Id₁ = kc_u

and

id₂ =k (V c_u +vc_S)/(V + v)

thus k =i_d2(V +v)/(V c_u +vc_S)

therefore cu =   i_d  vc_s/(i_d2-i_d1 )(V + v) + i_d1 v

Concentration of unknown, cu is therefore calculated. This procedure is sometimes reported as spiking used in environmental analysis.