Fig. 46. Selectivity for Pb²⁺ ions (50 nM) using a “turn-on” fluorescence sensor based on GQD/AuNP conjugates in the presence of interfering analytes including Mn²⁺, Fe³⁺, K⁺, Hg²⁺, Cu²⁺ Mg²⁺, Ca²⁺, Zn²⁺, Cd²⁺, and Ag⁺ ions (200 nM). Reprinted with permission from ref. 704, X. Niu, Y. Zhong, R. Chen, F. Wang, Y. Liu, D. A. Luo, “Turn-on” Fluorescence Sensor for Pb²⁺ Detection Based on Graphene Quantum Dots and Gold Nanoparticles, Sens. Actuators, B, 2018, 255, 1577–1581. Copyright© Elsevier.