Synthesis of Molecularly Imprinted Polymer on Surface of TiO2 Nanowires and Assessment of Malathion and its Metabolite in Environmental Water

Abstract

Molecularly imprinted polymer (MIP) for malathion and its major metabolite malaoxon was prepared with sol‒gel polymerization method using malathion as template molecule, (3-aminopropyl)triethoxysilane (APTES) as functional monomer, tetraethyl orthosilicate as crosslinker, TiO₂ nanowires as support and methanol as solvent. Interaction of APTES with malathion by hydrogen bond with a ratio of 2 : 1 was evaluated by the molecular recognition mechanism. The properties of MIP were characterized by Fourier transform infrared spectroscopy, scanning electron microscope, transmission electron microscope, X-ray diffractometry, surface area and porosimeter analysis, elemental analysis and thermogravimetric/differential thermal analysis. Molecularly imprinted polymers showed high affinity, recognition specificity and efficient adsorption performance for malathion. The residues of malathion and malaoxon in tap water were cleaned up by MIP-solid-phase extraction cartridge, determined by gas chromatography with flame photometric detector. The quantification limits of malathion and malaoxon were both 0.01 mg/L. The spiked recoveries of malathion and malaoxon in environmental water were 62.1‒76.7% (RSD 4.2‒6.5%) and 82.1‒95.4% (RSD 7.0‒7.7%), respectively. Gas chromatography‒tandem mass spectrometry analysis for confirmation was also performed.