Rapid and Sensitive Detection of Lead Ions Based on Backward Light Scattering Technique

This work presents a novel analytical method for detecting lead ions (Pb(II)) based on backward light scattering (BLS). The BLS intensity was significantly enhanced by the formation of ion-association complexes between ciprofloxacin (CIP), Congo Red (CR), and Pb(II) through electrostatic attraction and hydrophobic interaction in a Britton−Robinson (BR) buffer solution at pH 4.56. The maximum BLS peak was observed at 399 nm. The BLS intensity showed a linear relationship with Pb(II) concentrations ranging from 0.5 to 60.0 μM, with a limit of detection (LOD) of 50 nM. Studies on the BLS spectrum, absorption characteristics, and reaction mechanism were conducted, and optimal reaction conditions as well as the impact of interfering substances were investigated. This method was successfully applied to the determination of Pb(II) in environmental water samples, achieving recoveries between 91 and 104%, with a relative standard deviation (RSD) ≤ 4.7%. The proposed BLS method offers rapid analysis, high sensitivity, environmental friendliness, and good stability, providing a theoretical basis for real-time, online monitoring of lead ions using BLS technology.