Towards citizen science in food chemistry: Nitrite detection in high-fat food by integrating solid-phase extraction and electromembrane extraction on a microfluidic paper-based sensor.

Citizen science-based food quality survey is a new demand in monitoring and management of food quality with development of preventive medicine. In this work, a point-of-care testing (POCT) method was developed specifically for end users to detect nitrite in high-fat food. To avoid the preparation of complex samples in laboratory, a microfluidic paper-based analytical device (μPAD) integrated with solid-phase extraction (SPE) for fat removal and electromembrane extraction (EME) for nitrite separation in high-fat food samples was constructed. For same purpose, a laboratory-free pretreatment method for high-fat food was established, and smartphone-assisted colorimetric sensor was used as a detector for image capture and data analysis. The POCT method constructed specifically for end users showed a limit of detection (LOD) of 1.1 mg/kg. Overall, this paper provides new insights into citizen science as a valuable resource tool for researchers, policymakers, and public interested in understanding and addressing the challenges in food chemistry.