Flow Injection Phosphate Biosensor Based on PyOx-MWCNTs Film on a Glassy Carbon Electrode Using FFT Continuous Cyclic Voltammetry
A new flow injection enzymatic biosensor was designed for selective determination of phosphate ions. Pyruvate oxidase (PyOX) and multiwall cabon nanotubes (MWCNTs) were immobilized on the surface of a glassy carbon electrode by the nafion polymeric layer. The measurement method was based on fast Fourier transformation continuous cyclic voltammetry (FFTCCV) in which the charge under the peak calculated in a specific potential range. The characterization of the biosensor was studied by scaning electron microscopy (SEM) method. Experimental parameters affect the sensitivity of the biosensors, such as amounts of the cofactors, pH, and the pyruvate concentration, were optimized. Also the effect of scan rate, solution flow rate and buffer pH were studied. The results show that, the linear response range of the proposed biosensor was 1 to 100 mu M and the detection limit was calculated 0.1 mu M at a signal-to-noise ratio of 3. The biosensor showed good reproducibility and selectivity towards the other interfering anions. The long-term storage stability of the phosphate biosensor was studied.