Hydrogel microsphere-based portable sensor for colorimetric detection of nitrite in food with matrix influence-eliminated effect
Rapid and accurate nitrite ions (NO 2 − ) detection is necessary to ensure food safety. Herein, a new portable method for detecting NO 2 − using hydrogel microspheres is proposed. Specifically, N-(1-naphthyl) ethylenediamine (NED) was immobilized on sodium alginate (SA) to obtain the SA-NED conjugate via covalent linking. The SA-NED microspheres were prepared in a Ca 2+ solution using an extrusion strategy based on the strong chelation between SA and Ca 2+ . The SA-NED microspheres exhibited superior adsorption capacity for NO 2 − , which agrees with the Langmuir isotherm model. Then, based on the Griess reaction , a microsphere-based colorimetric sensor was developed for rapid, quantitative, and on-site NO 2 − detection via a smartphone-based sensing platform. The entire detection procedure can be completed within 35 min. The microsphere-based sensor exhibited a detection limit of 0.02 μg mL –1 with recoveries ranging from 89.7% to 104.8% in different food samples. Moreover, the microsphere-based sensor showed good tolerance to the complex food matrix. Water and milk samples could be directly measured without pretreatment , and pickles and sausages only required simple homogenization before measurements. Our study provides an effective approach for rapid and on-site monitoring of NO 2 − .
危险品化学品经营许可证（带存储）