Aptamer-modified magnetic nanoparticles for extraction of atrazine in environmental water samples

Abstract

In this work, a novel aptamer magnetic sorbent was prepared and used as magnetic solid-phase extraction sorbent for selective isolation of atrazine (ATZ) in water samples. The magnetic oligosorbent was fabricated by immobilizing DNA aptamer onto the surface of vinylized magnetic nanoparticles (VMNPs) via “thiol-ene” click chemistry reaction. After optimization of different aptamer coupling parameters, the following experimental conditions were found to give best results: 100 mg VMNPs incubated with 1 μmol L−1 thiol-modified aptamer for 5 h at 55 °C. The resulting oligosorbent was characterized by different instrumental techniques such as transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR) and inductively coupled plasma mass spectrometry (ICP-MS). Then, several parameters of the extraction protocol were investigated to achieve the best ATZ extraction performance. The optimized aptamer-based magnetic solid-phase extraction (Apt-MSPE) protocol followed by HPLC with diode-array detection gave detection and quantification limits for ATZ of 0.005 µg L−1 and 0.018 µg L−1, respectively. The applicability of this protocol was demonstrated by analyzing several environmental water samples from of different sources with recovery values from 85.5 to 94% and relative standard deviations less than 2.5%. Moreover, the developed Apt-MNPs sorbent could be re-used at least 12 times, without losses in its extraction capacity.