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Novel sequential separation and determination of a quaternary mixture of fungicides by using an automatic fluorimetric optosensor
摘要： A versatile flow-through multi-optosensor is proposed for the separation and spectrofluorimetric determination of mixtures of four widely used pesticides: carbendazim, thiabendazole, carbaryl and o-phenylphenol at μg g?1 levels in fruits. The flow system is based on the online pre-concentration and separation of the pesticides on a solid sensing microzone, followed by the sequential measurement of their native fluorescence. The separation of the pesticides takes place on a solid support located in the same flow cell, on which analytes are temporarily immobilized and separated from the matrix due to their different retention/desorption kinetics when they interact with the C18 silica gel microbeads. Suitable analytical parameters were obtained for the selected analytes, with method detection and quantification limits ranging between 0.1–0.5 and 0.2–1.6 μg g?1, respectively. These values comply with the maximum residue limits (MRLs) established by the Codex Alimentarius for these commodities; in addition, carbendazim, thiabendazole and ortho-phenylphenol comply with the MRLs of The European Union. The developed method was applied to the analysis of citrus fruits by performing recovery studies. Recoveries between 85% and 115% were obtained in all cases, and the results were confirmed by a liquid chromatography–mass spectrometry reference method.
关键词： pesticide,ortho-phenylphenol,thiabendazole,automation,carbaryl,carbendazim,citrus fruits,SIA,solid-phase spectroscopy
更新于2025-09-23 15:22:29
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A new nanocomposite optical sensor based on polyurethane foam and gold nanorods for solid-phase spectroscopic determination of catecholamines
摘要： A new nanocomposite material based on gold nanorods and polyurethane foam was obtained, and a method for the determination of catecholamines with the use of this nanocomposite modified with silver nitrate was developed. The determination is based on the measuring hypsochromic shift of a short-wave surface plasmon resonance band in a diffuse reflection spectrum of the nanocomposite. This shift is caused by reduction of silver from silver ions on the surface of gold nanorods under the influence of catecholamines. Effects of time, pH, volume of the reaction mixture, concentration of silver ions, and catecholamines on the interaction were examined. The proposed method allows to determine dobutamine, epinephrine, norepinephrine and dopamine with the detection limits of 0.1, 0.07, 0.07, and 0.05 μg mL?1, respectively. The developed method can be applied to analysis of medicines.
关键词： Nanocomposite,Au nanorods,Surface plasmon resonance,Polyurethane foam,Catecholamines,Solid-phase spectroscopy
更新于2025-09-12 10:27:22