Detection of melamine based on the suppressed anodic response of uric acid by a AueAg nanoparticles modified glassy carbon electrode   全文下載

We demonstrated a sensitive electrochemical method for the determination of nonelectroactive melamine (Mel) using a modified glassy carbon electrode (GCE), with uric acid (UA) as the signal reporter. To increase the anodic response of UA, GCE was coated with AueAg nanoparticles and a Nafion thin film (AueAg/Nafion/GCE). The sensing mechanism was based on the competitive adsorption behavior of Mel on the AueAg/Nafion/GCE, which reduces the electroactive surface area of nanoparticles and thus hinders anodic response of UA. Under optimal conditions and the use of an analytical method of differential pulse voltammetry, this modified electrode detected Mel concentrations ranging from 2.5 to 70 nM, with a detection limit of 1.8 nM. The AueAg/Nafion/GCE demonstrated satisfactory reproducibility and stability, with relative standard deviations (RSDs) of 9.3% and 7.1%, respectively. The proposed electrochemical method was then successfully used to determine the Mel content in spiked milk powder and cat food samples, with RSDs of 1.7%e9.3% and recoveries of 92.4%e103.7%.