A novel colorimetric sensor based on modified mesoporous silica nanoparticles for rapid on-site detection of nitrite

A novel colorimetric sheet based on Griess reagent–doped mesoporous silica nanoparticles was developed for nitrite detection. Griess reagent was adsorbed on long–range ordered hexagonal mesoporous silica nanoparticles and developed ink–bottle pores with some disorder. When the modified nanoparticles were bound using starch to fabricate a thin (~ 313 μm) colorimetric sheet, spherical particles with a rougher surface and some distortion of their mesoporosity were observed. The sheet was used in conjunction with digital image colorimetry (DIC) and provides a wide linear range of 0.05 to 2.50 mg L⁻¹ with a low detection limit (15.0 μg L⁻¹–NO₂⁻, equal to 4.5 μg L⁻¹ NO₂⁻–N), good inter-day precision (1.93%RSD), and excellent precision (2.67% relative error). The colorimetric sensors produced from the sheet costs only 0.04 USD each, while the DIC uses a standard smartphone for photographic detection. The method developed offers an easier and cheaper means of conducting rapid on-site determination of nitrite in water with reliable quantitative results.