Smartphone-assisted colorimetric detection of arsenic using Co-functionalized silver nanoparticles in agarose gel matrix

A novel colorimetric sensor for the sensitive and rapid detection of arsenic ions (As³⁺) was developed using starch and citrate co-functionalized silver nanoparticles embedded into an agarose gel matrix (SC–AgNP/AG Gel). The SC-AgNP/AG gel was synthesized, and their characteristics analysis such as UV, SEM, XRD, and FTIR were extensively studied. Upon exposure to arsenic, the color response of the sensor changed from yellowish-brown to reddish, facilitating visual identification without the need for complex equipment. Smartphone-based colorimetric detection demonstrated a linear response in the concentration range of 0–50 ppm and a detection limit of 1.11 ppm. Validation of sensor was conducted using Atomic absorption spectroscopy and the results showed a significant correlation coefficient (R² = 0.97). The sensor exhibited an excellent selectivity to As³⁺, stability up to 30 days at 4 °C, sensitivity and reproducibility. SC-AgNP/AG gel was found to benefit in the practical applications such as environmental monitoring and food safety due to its simplicity, stability and ease of operation.