Electrochemical Detection of H2O2 Using an Activated Glassy Carbon Electrode

Hydrogen peroxide (H2O2) is extensively used for sterilization purposes in the food industries and pharmaceuticals as an antimicrobial agent. According to the Food and Agriculture Organization (FAO), the permissible level of H2O2 in milk is in the range of 0.04 to 0.05% w/v, so it has been prohibited to use as a preservative agent. Herein, we reported the electrochemical sensing of H2O2 in milk samples using an activated glassy carbon electrode (AGCE). For this purpose, activation of GCE was carried out in 0.1 M H2SO4 by continuous potential sweeping between −0.7 to 1.8 V for 25 cycles. The AGCE showed a redox peak at -0.18 V in the neutral medium corresponding to the quinone functional groups present on the electrode surface. AGCE was studied in (pH 7.4) 0.1 M PBS for the electro-catalysis of H2O2. The surface of the activated electrode was analysed by Raman spectroscopy and contact angle measurements. In addition, for the activated surface, the contact angle was found to be 85° which indicated the hydrophilic nature of the surface. The different optimization parameters such as (1) effect of electrolyte ions, (2) electrooxidation cycles, and (3) oxidation potential windows were studied to improve the activation process. Finally, AGCE was used to detect H2O2 from 0.1 to 10 mM and the limit of detection (LOD) was found to be 0.053 mM with a linear correlation coefficient (R2) of 0.9633. The selectivity of the sensor towards H2O2 was carried out in the presence of other interferents. The sensitivity of the AGCE sensor was calculated as 17.16 μA mol cm−2. Finally, the commercial application of the sensor was verified by testing it in milk samples with H2O2 in the recovery range of 95%–98%.