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Herein, we report a novel, disposable electrochemical sensor for the detection of nitrite ions in food samples based on the sonochemical synthesized orthorhombic CaFe2O4 (CFO) clusters modified screen printed electrode. As synthesized CFO clusters were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transformer infrared spectroscopy (FT-IR), Thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and amperometry (i-t). Under optimal condition, the CFO modified electrode displayed a rapid current response to nitrite, a linear response range from 0.016 to 1921 µM associated with a low detection limit 6.6 nM. The suggested sensor also showed the excellent sensitivity of 3.712 μA μM−1 cm−2. Furthermore, a good reproducibility, long-term stability and excellent selectivity were also attained on the proposed sensor. In addition, the practical applicability of the sensor was investigated via meat samples, tap water and drinking water, and showed desirable recovery rate, representing its possibilities for practical application.

A straightforward green fabrication of electrochemical assay for high sensitive quantitative detection of methyl parathion (organophosphate pesticide) via colloidal gold nanoparticles (AuNPs) modified glassy carbon electrode. Methyl parathion is widely known for its unpleasant functions in bio and ecological system. The synthesis utilizes tannic acid as a bi-functional reducing cum stabilizing agent under ambient temperature (25 °C). The colloidal TA@AuNPs were characterized through TEM, UV–vis, X-ray diffraction, and FT-IR spectroscopy. Fabricated TA@AuNPs/GCE assay has superior electrocatalytic activity toward MP in terms of a wide dynamic range (0.033–167.7 µM), and lower limit of detection (10.5 nM). In addition, the sensor displayed high selectivity, good reproducibility and stability. The practicality of fabricated electrode was verified through the determination of MP in various food and water samples.