Fluorescence sensing of phosdrin pesticide by the luminescent Eu(III)- and Tb(III)-bis(coumarin-3-carboxylic acid) probes

• Eu(III) or Tb(III)-complex has been characterized by spectroscopic techniques.
• The interactions of complexes with different pesticides have been investigated.
• The binding constants of the Eu and Tb-complex with Phosdrin have been determined.
• Detection limits were 6.28 and 1.07 μM for Eu and Tb-complex, respectively.
• Selective Ln(III)-complex has been suggested for determination Phosdrin.

Luminescence quenching of the Eu(III)- and Tb(III)-bis (coumarin-3-carboxylic acid) (Ln(III)-(CCA)2) probes has been studied in the presence of organophosphorus or organochlorine pesticides; Phosdrin (P1), Malathion (P2), Profenofos (P3), Formothion (P4), Heptachlor (P5), and Endosulfan (P6). The luminescence intensity of lanthanide complex probes Ln(III)-(CCA)2 decreases as the concentration of the Phosdrin pesticide increases, while the other investigated pesticides have no significant influence on the lanthanide fluorescent intensities. It is observed that the quenching of Eu(III) and Tb(III)-coumarin-3-carboxylic acid by Phosdrin proceeds via static quenching processes according to Stern–Volmer plot. The binding constants (K) and the thermodynamic parameters of the interaction of Ln(III)-(CCA)2 with Phosdrin have been determined. A direct method for the determination of the Phosdrin in ethanol has been developed based on the luminescence changes of the Ln(III)-(CCA)2-phosdrin ternary complexes. The detection limits of P1 were 6.28 and 1.07 μM in case of Eu(III) and Tb(III)-complex, respectively. The influence of various interfering species on the detection of P1 has been investigated to assess the analytical applicability of the method. The new method was applied to determine the Phosdrin pesticide in different types of water samples.

The emission spectra of (A) Eu(III)-(CCA)2 and (B) Tb(III)-(CCA)2 complexes in different solvents.Figure optionsDownload as PowerPoint slide