Electrochemical detection of nitrite at NiFe2O4 nanoparticles synthesised by solvent deficient method

A sensing platform with NiFe2O4 nanoparticles integrated into carbon paste for the electrochemical determination of nitrite has been developed. Spinel NiFe2O4 nanoparticles were synthesised via a simple solvent deficient method and investigated by X-ray diffraction (XRD), Fourier transfer infrared spectroscopy (FTIR), Brunauer-Emmett-Teller (BET) and Scanning electron microscopy (SEM), for their structural and morphological characteristics. The NiFe2O4 integrated carbon paste electrode (NiFe2O4-CPE) displayed enhanced catalytic activity towards oxidation of nitrite than the bare electrode in phosphate buffer solution (PBS) of pH-7 owing to the synergistic effect arising from the mixed metals. The electrochemical response of NiFe2O4-CPE under the influence of several parameters such as effect of scan rate, catalyst-carbon ratio and the concentration of analyte was studied. The oxidation of nitrite was found to be a diffusion controlled process as the oxidation currents varied linearly with scan rate and concentration of the analyte. The diffusion coefficient and rate constant for nitrite oxidation was found to be 3.71 x 10(-5) cm(2) s(-1) and 9 x 10(8) cm(3) mol(-1) s(-1) respectively. The sensing platform demonstrated a nitrite detection limit of 0.1236 mu M(S/N = 3) with a wide linear range between 0.1 and 1000 mu M and a sensitivity of 7.9617 mu A mu M-1 cm(-2).