91. Solving a chemistry problem

5. The drug phytin is quantitatively precipitated by lead ions. The amperometric determination of phytin by titration with a solution of lead nitrate is based on this reaction. On a dropping mercury electrode against the background of lithium chloride, both phytin (E1/2 = -1.50 V) and lead ion (E1/2 = -0.43 V) are reduced. Assess the possibility of amperometric titration of phytin with a solution of lead nitrate at potentials of -0.10 V, -0.80 V and -1.70 V. What shape do the titration curves have at these potentials?