Cork-based electrochemical sensors obtained by laser-induced graphene: A green alternative for sodium nitrite detection in beverage samples

A laser-pyrolyzed cork-based electrochemical sensor is proposed for the determination of sodium nitrite, a widely used food additive that poses potential health risks. The pyrolysis parameters were varied individually, and electrochemical performance was compared to select the conditions that provided the highest conductivity and sensitivity. Additionally, a chemical treatment with a waterproofing spray was applied to enhance sensor stability and ensure reproducible measurements. The proposed sensor was characterized by scanning electron microscopy (SEM), X-ray energy dispersive spectroscopy (EDS), attenuated total reflectance Fourier-transform infrared spectroscopy (ATR-FTIR), Raman spectroscopy, X-ray diffraction (XRD), and thermogravimetric analysis (TGA). The performance of the sensor was evaluated for sodium nitrite detection in different beverage samples, including wine, orange juice, and mineral water. The results demonstrated a linear response range from 300 to 1000 μmol L⁻¹, with a limit of detection of 14.4 μmol L⁻¹. Recovery tests indicated satisfactory accuracy, with values ranging from 86.1% to 110.8%, confirming the method's applicability to real samples. The results of this study reinforce the potential of cork as a sustainable substrate for high-performance electrochemical sensors, a viable and promising alternative for food analysis, replacing less eco-friendly conventional substrates.