A novel approach to Hg2+ determination in water samples using carbon dots based on paper and fluorescence digital image analysis

This work proposes the use of a simple inexpensive method for the hydrothermal synthesis of fluorescent carbon dots nanoparticles (CDs) from rice starch aimed at the determination of Hg2+ in water. The proposed method involved using a paper‐based analytical device coupled to a 3D plate, with a UV‐LED chamber and a smartphone for the acquisition and analysis of the fluorescence digital images of the CDs.The size of the carbon dots ranged from 0.5 to 3 nm, with an average particle size of approximately 1 nm. The functionalization of carbon dots with methimazole allowed a high selective for Hg2+ determination. The results obtained showed a linear response R2 of 0.997 and Hg2+ concentration in the range of 0.5 to 45.0 μΜ with a LOD and LOQ of 0.23 and 0.62 μmol L‐1, respectively. The results of the study show that there are no significant differences, at 95% confidence level, between the data obtained from the application of the proposed method and the reference method.The proposed method is in line with the principles of green chemistry, as it involves the use of renewable sources for starch extraction and a hydrothermal synthesis process that does not employ toxic reagents. In addition, the method employs only 15 μL of reagent/sample.This article is protected by copyright. All rights reserved.