SiO2/Al2O3/C grafted 3-n propylpyridinium silsesquioxane chloride-based non-enzymatic electrochemical sensor for determination of carcinogenic nitrite in food products

The excessive uptake of nitrite is perilous and detrimental for human health that prone to cancer disease. Herein, described the synthesis of SiO2/Al2O3/C material through the sol-gel procedure followed by grafting with 3-n propylpyridinium silsesquioxane chloride organic ligand for enhancing electrochemical activity. H-NMR, 13C NMR, and 29Si studies were performed for confirmation of surface functionalization through the grafting technique. The surface morphology was evaluated through SEM and TEM techniques. The material showed an irregular and flakes-like structure that exhibited more compactness and conglomerate structure with no segregation in phase was observed after grafting. The elemental composition was confirmed from EDX analysis. The electrochemical measurements were performed with cyclic voltammetry, electrochemical impedance spectroscopy (EIS), and chronoamperometry. The prepared hybrid inorganic-organic composite Si/C/Al/SiPy+Cl- was applied for the modification of the glassy carbon (GC) electrode and assessed as a sensor for nitrite determination. The sensor showed the low limit of detection (0.01 μM), low limit of quantification (0.08 μM), wide linear response range (0.2-280 μM), and high sensitivity (410 μA·μM-1). It gave a quick response time of <1 s in the presence of 70 μM nitrite. The fabricated sensor showed high sensitivity, chemical stability, and insignificant interference from co-existing species present in sausage meat and food industry discharges. The repeatability of the sensor was evaluated as 2.5 % R.S.D.; for n = 10 at 50 μM nitrite.