A Point Of Care Testing System For Chemical Oxygen Demand Based On Graphene Oxide. Nickel Nanoparticles Modified Electrode

An electrochemical analysis system for rapid determination of chemical oxygen demand (COD) in flow state was established. A planar electrode modified with GO-NiNPs was matched with a 3D printed thin layer cell. The sample was driven smoothly through the electrode surface by a micro peristaltic pump and then measured by chronoamperometry. The effect of modified materials, dielectric and electrochemical operating conditions were investigated. The whole response time of COD was 1.5 min and the demand for the sample was about 2 mL. It turned out that the linear range of response in the low concentration region was 0.15 100 mg/L, the linear equation was i(A) = 3.974c (mg/L) + 0.2295 (r = 0.9991) and the detection limit was 0.04 mg/L. The linear response range in the high concentration region was 100 450 mg/L, and the linear equation was i(A) = 1.938c (mg/L) + 230.9 (r = 0.9877). Compared with the national standard method (GB11914-89) for measuring the actual water samples (Qinhuai River, Xuanwu Lake and Nanjing tap water), the correlation between them was quite good and the analysis time was dropped to 1/100. This new sensing system provided an environmentally friendly and portable method for detection of COD without using expensive, highly corrosive and toxic reagents.