Characterization of Paraoxon-ethyl and Parathion-ethyl Complexes with β-Cyclodextrin Modified Zirconium Oxide Thin Films by Infrared Spectroscopy

The detection of organophosphate compounds was demonstrated using sol–gel materials made of zirconia composite films. The detection was performed via inclusion complexes of the organophosphates of paraoxon-ethyl and parathion-ethyl with the zirconium dioxide-β-cyclodextrin composite film. The formation of sol–gel thin film process was investigated and optimized. The morphology of zirconium dioxide with β-cyclodextrin gel was characterized by scanning electron microscopy and energy-dispersive spectroscopy. Attenuated total reflectance Fourier transform infrared spectroscopy was used for the characterization of the inclusion complexes of paraoxon-ethyl and parathion-ethyl on zirconium dioxide with β-cyclodextrin film. The hydrolysis of paraoxon-ethyl by zirconium dioxide with the β-cyclodextrin gel thin film caused peak shifts in the attenuated total reflectance Fourier transform infrared spectra. The increase in absorption intensity correlated with increasing paraoxon-ethyl concentration, but this trend was not observed for parathion-ethyl. The hydroxyl vibration band of the intermolecular and intramolecular hydrogen bonds was observed to decline with increasing paraoxon-ethyl concentration. Quantitative analysis of paraoxon-ethyl using attenuated total reflectance Fourier transform infrared spectra provided a linear calibration relationship from 1 to 7 µM with a limit of detection as low as 30 nM.