A novel chemiluminescent probe based on the oxidase-like activity of pyrite quantum dots for the determination of copper in food samples

Pyrite (FeS2) quantum dots (PQDs) exhibit outstanding oxidase-like activity, which can be a ground to apply them in the chemiluminescence (CL) systems. Herein, we show that PQDs in combination with luminol as an efficient CL reagent, create a powerful sensing platform. These QDs effectively catalyze the luminol oxidation with dissolved O2, producing an intense CL signal. Copper ions, having a great affinity to sulfur atoms on the surface of PQDs, adsorb onto the surface of QDs and inhibit their catalytic action, and so, diminish the CL in-tensity. Utilizing this effect, luminol-O2-PQDs in alkaline medium was established as a sensitive probe to determine copper in the concentration range of 2.0-100 nM with LOD of 1.2 nM. The validation of the method was performed by analysis of NIST certified reference materials, and high correlation between obtained con-centration and reported values was obtained. Furthermore, the probe was applied to the detection of copper in mushroom, sunflower seeds and flour samples and comparison of the results with those obtained from a standard method approved its accuracy. Luminol-PQDs CL probe is a simple, selective, sensitive and low-cost tool for determination of copper in nutrition sources.