A Simple Method for Copper Ion Determination in Beverages Using Mn-Modified CdTe/CdS Quantum Dots as a Fluorescence Probe

Based on the fluorescence quenching of Mn-modified CdTe/CdS quantum dots (QDs) by Cu2+, a simple, rapid and specific quantitative method for Cu2+ in beverages including juices, coffees and white wines was proposed. Under the optimal conditions, a linear relationship was observed between the extent of fluorescence quenching and the concentration of Cu2+ in the range of 0.32-32 mu g . L-1 with an excellent correlation coefficient of 0.9992. The limit of detection (LOD) based on three times ratio of standard deviation of blank measurements (n = 10) to Stern-Volmer quenching constant was 0.16 mu g . L-1. The recovery of Cu2+ standard solution spiked with samples was in the range of 87.74-110.5% with the relative standard deviations less than 10%. The concentrations of Cu2+ in the samples obtained by the proposed method were in good agreement with those assayed by the atomic absorption spectrophotometric method.