Portable platform for smartphone-enabled arsenic detection using hydride generation and a silver-based metal-organic framework sensor

A portable sensor device was developed for on-site detection of arsenic (As(III)) using the hydride generation technique. The 3D-printed millifluidic device includes two zones: one for sample preparation and another for detection. The sensor zone consists of a silver-based metal-organic framework (Ag-MOF) immobilized with a polyvinylidene fluoride (PVDF) coating on a 3D-printed lid. The arsenic hydride (AsH₃) generated in the sample preparation well reacts with the immobilized Ag-MOF, generating silver nanoparticles (AgNPs) that cause the color change from white to dark brown. Visual detection and colorimetric quantification were performed using a 3D-printed portable photo box with LED light panels, a smartphone for image capture, and ImageJ software for RGB analysis. The system required only 1 mL of sample and 5 min for the color reaction. Under optimal conditions, the method exhibited good linearity in two concentration ranges: 20–100 µg L⁻¹ (low range) and 100–500 µg L⁻¹ (high range). The detection limit (LOD) was 10 µg L⁻¹, and the quantification limit (LOQ) was 20 µg L⁻¹. Precision, expressed as relative standard deviation (RSD), ranged from 12.9 % to 9.5 %, with recoveries between 91 % and 104 % in milk and groundwater samples. Results were validated against ICP-OES and assessed using the AGREE and BAGI metric tools, confirming the method’s sustainability and practicality.