The Development of the Fluorescence-based Portable Device for Lead (II) and Formalin Determination in Food Samples by...

The fluorescence-based portable device for the determination of lead (Pb²⁺) and formalin (FA) in food samples by using Nitrogen-doped carbon dots (N-CDs) as a fluorescence probe was developed. The proposed approach, Pb^2+, and FA were determined based on the photo-induced electron transfer (PET) mechanism and the silver mirror reaction. The fluorescence intensity of the N-CDs decreased with the increase of Pb²⁺ concentration and increased with the increasing FA concentration. The fluorescence intensity of N-CDs after the reactions were measured by a filter-free fluorometer platform using a commercial camera module and a Raspberry Pi, a compact computer, as a detector and processor. The experimental results were obtained using control samples with known Pb²⁺ and FA concentrations in the 0.01-10 mg L^- 1 and 25-150 mg L^- 1, respectively. The proposed approach is simple, low-cost, and accurate for the on-site monitoring of Pb²⁺ and FA in various food samples. Of utmost importance, the proposed approach is expected to be a pioneering model for the future development of other analytes with a broad range of practical applications.