Inclusion Complex of O -phthalaldehyde-Buprofezin with Dimethyl-β-Cyclodextrin Using Thermochemically-Induced Fluorescence Derivatization (TIFD) Method and its Analytical Application in Waters

Improvement of the TIFD method to determine buprofezin (BUP) founded on the O -phthalaldehyde (OPA)-thermoproduct complex of buprofezin (OPA-BUP) with dimethyl-β-cyclodextrin (DMβCD) was investigated at 25 °C. The TIFD method developed in DMβCD medium, was optimized with respect to the reaction time, DMβCD concentration and pH. Based on the inclusion reaction, the OPA-BUP: DMβCD inclusion complex was developed in two aqueous media pH 7 and pH 13. A 1:1 stoichiometric ratio of OPA-BUP: DMβCD complex was obtained. The binding constants (K) and Gibbs energy (ΔG°) values increasing and decreasing with pH, respectively, show the spontaneous and thermodynamically favorable at 25 °C of the inclusion complexes formation. Normalized TIFD spectra were measured at 425 nm for emission and at 345 nm for excitation. Limits of detection (LOD) and quantification (LOQ) obtained, according to the pH, were in the ranges 0.05–0.1 ng mL ̶ 1 and 0.2–0.4 ng mL ̶ 1 , respectively. Relative standard deviation (RSD) values, less than 1.3% corroborated TIFD method repeatability in DMβCD medium. Solid phase extraction (SPE) procedure which was used for quantitative analysis of natural water samples collected from Niayes area, led to satisfactory recovery rates values 99.5–117.3%.