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Highly stable and photoluminescent methylammonium lead halide perovskite quantum dots (MAPbBr3 PQDs) have been synthesized and applied for the fluorescence quenching detection of clothianidin in fruit and vegetable samples. Characterizations using different techniques, including photoluminescence (PL), X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and time-resolved PL (TRPL), show that static quenching is the dominant fluorescence quenching mechanism of MAPbBr3 PQDs with clothianidin. Hydrogen bonds or van der Waals forces play major roles in the MAPbBr3 PQDs–clothianidin interaction. Under optimized conditions, the relative PL intensity of MAPbBr3 PQDs is linear to the concentration of clothianidin in the 0.0 and 20.0 mg/L range with a detection limit of 0.17 μg/kg. Excellent recoveries of 79.5–115.4% were acquired for radish and banana samples with a relative standard deviation below 9.4%. These results indicate that PQDs can be used for qualitative and quantitative identification of clothianidin, providing an effective detection method for risk prevention and control of neonicotinoid pesticide residues in agricultural products. [ABSTRACT FROM AUTHOR]

In the current study, an effective and simple procedure of extraction for the four benzophenone compounds from water samples was achieved by dispersive liquid–liquid microextraction (DLLME) based on the solidification of floating organic droplets (SFO) with a natural monoterpene enol as the extractant. As a natural, high solidification point, inexpensive, and environmentally friendly hydrophobic solvent, α−terpineol was selected firstly as an extractant for DLLME and could be collected and transferred easily after extraction by solidification at a lower temperature. Several main parameters closely related to extraction efficiencies, such as volume of extractant, extraction time, pH and salt concentration of the sample solution, temperature, and time of the solidification process, were investigated in detail. The results showed that the established method had good extraction performance for benzophenone compounds with enrichment factors in the range of 29–47. Furthermore, the linearities were over the range of 2–2000 µg/L, and the limits of detection were 0.12–0.53 µg/L for four benzophenone compounds. The recoveries ranged from 80.2% to 108.4%, with RSDs (intra- and inter-assay) less than 8.5%. At last, the method applicability was investigated by the determination of the benzophenone compounds in aqueous solutions, and satisfactory recoveries (83.0–107.0%) were acquired. Taken together, α−terpineol, a natural monoterpene enol, was first used as an extractant of DLLME-SFO, which provided an alternative method with simplicity and rapidity for the determination of benzophenone compounds in aqueous samples. [ABSTRACT FROM AUTHOR]