A photoresistor-based portable digital sensor for rapid colorimetric detection of Arsenic

Abstract

The contamination of water sources with Arsenic from natural and human activities is one of the most critical global issues today. Now more than ever, it is essential to conduct continuous real-time assessments of water quality to identify the presence of Arsenic pollutants and address potential threats. However, the majority of existing laboratory and portable techniques are either expensive or time-consuming due to the expert-driven complexity of their analysis processes. This study presents colorimetric sensors for the on-site quantitative liquid-phase detection of Arsenic in water, vegetables, and rice. These sensors electronically measure the change in the color intensities of different Arsenic concentrations. The sensor was converted to a point-of-care testing (POCT)/portable device prototype and calibrated with known samples before testing with the real samples. The calibration plot showed that the intensity of the color change was proportional to the change in the resistance of the LDR. The prototype was further translated into a Portable device. The device can be used to monitor Arsenic in real samples. This device is specific, stable, and user-friendly, allowing for the rapid detection of the Arsenic contaminant in water and vegetables, and can detect Arsenic in the range of 8–100 µg/L. In the study, the LOD was 8 µg/L (ppb), and RSDs for spiked water samples were 1.01 %. For spiked through boiled vegetables and rice, RSD was 2.08 %, and for spiked soaked samples, it was 2.52 %, in comparison to AAS measurements.