Zn2+ conjugated Schiff base organic nanoparticles for selective quantification and degradation of diethyl chlorophosphate in aqueous media: Application to green vegetables

Abstract

In the present work, zinc conjugated Schiff base organic nanoparticles have been fabricated and explored for the quantification and degradation of diethyl chlorophosphate (a common pesticide for green leafy vegetables). Primarily, a Schiff base (SB) was derived by the condensation of 2-hydroxy-4-methoxybenzophenone and 2-aminoethanol and then, it was transformed into organic nanoparticles by reprecipitation method. Further, the Zn2+ ions were added to dispersion of organic nanoparticles (SB-ONPs) to form zinc conjugated Schiff base organic nanoparticles (ZnSB-ONPs). Their conjugation turns ‘ON’ the spectrofluorimetric response and displayed an elevated emission band centered at 435 nm. Further, the emission signal of ZnSB-ONPs was quenched in the presence of diethyl chlorophosphate with visual appearance of HCl gas which indicated breakage/formation of bonds. Therefore, a detailed investigation of recognition and degradation of diethyl chlorophosphate was accomplished by spectrofluorimetric, spectroscopic (1H NMR and 31P NMR) and mass spectrometric experiments. The use of Zn2+ ions in conjugation with Schiff base organic nanoparticles (in ZnSB-ONPs) offered some advantages like selective spectrofluorimetric recognition and degradation of diethyl chlorophosphate, quantification of diethyl chlorophosphate up to nano-molar levels (LOQ = 55.2 nM), and application of developed protocols in aqueous media to green leafy vegetables and tea samples.