Micellar-enhanced thermochemically induced fluorescence derivatization (ME-TIFD) method for the determination of metolachlor herbicide residues in water

Abstract A sensitive micellar-enhanced thermochemically induced fluorescence derivatization (ME-TIFD) method for a rapid determination of metolachlor (MET) residues based on the O-phthalaldehyde (OPA)-thermoproduct complex of MET (OPA-MET) was investigated. Both SDS and Brij-700 have been used as surfactant micelles. This study advocates the TIFD method analytical parameters curation. Fluorescence enhancement and its stabilization were highlighted for the OPA-MET equimolar complex in micellar aqueous solutions. The new analytical features (K: binding constant and ΔG°: Gibbs energy) for controlling thermodynamic interactions were carried out at 25 °C. Under the optimized conditions, the calibration curves were linear with correlation coefficients ranging from 0.9788 to 0.9896 at the concentration level of 10-580 ng mL–1, and the limits of detection were 0.04-0.7 ng mL−1 at a signal-to-noise (S/N) of 3. The SPE/ME-TIFD applications combined with analysis of well and tap water spiked samples with metolachlor yield satisfactory mean recoveries (RSD) 102.2–108.1% (5.1–7.3%) and 103.6–106.0% (6.3–7.6%), respectively.