Fluorescence analysis of cobalt(ii) in water with β-cyclodextrin modified Mn-doped ZnS quantum dots

Abstract

The analysis of Co²⁺ in agricultural water is of great importance for the healthy growth and safe supply of crops. β-Cyclodextrin (β-CD) modified Mn-doped ZnS quantum dots (β-CDs@QDs) were proposed as fluorescence (FL) probes for Co²⁺ analysis in water. Mn-doped ZnS QDs were synthesized by the chemical precipitation method, and a simple one-step heating approach in acidic aqueous solution was introduced to surface modify the QDs with β-CDs. The FL emission around 590 nm of β-CDs@QDs was found to be quenched in the presence of Co²⁺. The probe was found to have a limit of detection (LOD) of 0.26 μmol L⁻¹ and a linear range of 1–10 μmol L⁻¹. The quenching mechanism of β-CDs@QDs for Co²⁺ might be a combination of inclusion complexation, encapsulation interaction, binding interaction, and FL resonance energy transfer. This probe was finally successfully used to analyze Co²⁺ in spiked irrigation water near two factories. With the advantages of simple preparation and capability of rapid FL analysis, β-CDs@QDs might be a potential probe for metal ion analysis in water.