Rapid Photoluminescence Quenching Based Detection of Cu²⁺ in Aqueous Medium by CdS Quantum Dots Surface Passivated by Thiourea

Abstract

Presented here is a simple yet rapid and efficient analytical method for visual as well as spectroscopic method for sensing of trace concentrations of Cu²⁺ ions in aqueous medium by systematic photoluminescence quenching of a highly water soluble probe made of CdS quantum dots surface modified by thiourea. The salient features of this work describe rapid detection (2 min equilibration time) of Cu²⁺ ions at wider linear concentration range (0.025 – 10 mg/L) corresponding to a sensitivity of 2.81(mg/L)⁻¹ and limit of quantification of 47.3 μg/L, respectively, suitable for Cu²⁺ sensing in drinking water and ground water. Further, the detection of Cu²⁺ ion was free from most interfering cations and anions, except for minor interference from Cr³⁺, Hg²⁺ and Pb²⁺. The robustness of our probe for Cu²⁺ sensing is demonstrated from efficient Cu²⁺ spike recovery analysis in groundwater and river water samples.