Electrocatalytic reduction of hydrogen peroxide and its determination in antiseptic and soft-glass cleaning solutions at phosphotungstate-doped-glutaraldehyde-cross-linked poly-L-lysine film electrodes

摘要

The present work describes the electrocatalytic behavior of phosphotungstate-doped glutaraldehyde-cross-linked poly-L-lysine (PLL-GA-PW) film electrode towards reduction of hydrogen peroxide (H_2O_2) in acidic medium. The modified electrode was prepared by means of electrostatically trapping the phos-photungstate anion into the cationic PLL-GA coating on glassy carbon electrode. The PLL-GA-PW film electrode showed excellent electrocatalytic activity towards H_2O_2 reduction in 0.1 M H_2SO_4. Under the optimized conditions, the electrochemical sensor exhibited a linear response for H_2O_2 concentration over the range 2.5 × 10~-6 to 6.85 × 10~-3 M with a sensitivity of 1.69 μA mM-1. The curvature in the calibration curve at high concentration is explained in terms of Michaelis-Menten (MM) saturation kinetics, and the kinetics parameters calculated by three different methods were compared. The PLL-GA-PW film electrode did not respond to potential interferents such as dopamine, ascorbic acid and uric acid. This unique feature of PLL-GA-PW film electrode allowed selective determination of H_2O_2. Finally, the proposed electrochemical sensor was successfully applied to determine H_2O_2 in commercially available antiseptic solution and soft-contact lenses cleaning solution and the method has been validated using independent estimation by classical potassium permanganate titration method. Major advantages of the method are simple electrode fabrication, stability and high selectivity towards hydrogen peroxide.