Identification of adulterated vegetable cooking oils using fluorescence quenching method with aqueous CTAB-coated CdSe/ZnS quantum dots as probes

A rapid and low-cost sensor based on fluorescence quenching of CdSe/ZnS quantum dots (QDs) was investigated for identification of adulterated vegetable cooking oils. High quality hydrophilic photoluminescent microspheres were synthesized by encapsulating hydrophobic QDs into the micelle of surfactants CTAB via phase transfer method. Fluorescence spectroscopy was used for characterization. The fluorescence intensity of prepared CTAB-coated QDs was selectively quenched by some components of the directly added adulterated oils. Fluorescence measurements were conducted and quantitative relationships between quenching and adulteration were analyzed. The developed sensitive sensor could detect refined used oils at 2% or higher concentrations in soybean oil.