Figure 6a: Cyclic voltammograms obtained at Poly (alanine) modified CPE in 0.2M PBS (pH 7.0) in pH values (5.7, 6.0, 6.5, 7.0, 7.5, 8.0) containing 0.1 × 10-3 mol L-1 PA at scan rate 50 mVs-1.