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Time-resolved fluorescence sensing of pesticides chlorpyrifos, crotoxyphos and endosulfan by the luminescent Eu(III)-8-allyl-3-carboxycoumarin probe.

Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy (2015-04-16)
Hassan A Azab, Gasser M Khairy, Rasha M Kamel
ABSTRACT

This work describes the application of time resolved fluorescence in microtiter plates for investigating the interactions of europium-allyl-3-carboxycoumarin with pesticides chlorpyrifos, endosulfan and crotoxyphos. Stern-Volmer studies at different temperatures for chlorpyrifos and crotoxyphos shows dynamic and static quenching mechanisms respectively. Direct methods for the determination of the pesticides under investigation have been developed using the luminescence variations of the probe in solution. The detection limits are 6.53, 0.004, 3.72 μmol/L for chlorpyrifos, endosulfan, and crotoxyphos, respectively. The binding constants and thermodynamic parameters of the pesticides with probe were evaluated. A thermodynamic analysis showed that the reaction is spontaneous with negative ΔG. Effect of some relevant interferents on the detection of pesticides has been investigated. The new method was applied to the determination of the pesticides in different types of water samples (tap, mineral, and waste water).

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Europium(III) chloride hexahydrate, 99.99% trace metals basis
Sigma-Aldrich
Paraoxon-ethyl, ≥90%, oil
Sigma-Aldrich
Europium(III) chloride hexahydrate, 99.9% trace metals basis