Vortex-assisted Dispersive Solid-phase Extraction Using Schiff-base Ligand Anchored Nanomagnetic Iron Oxide for...

Phthalate esters are synthetic chemicals that are widely used in plastic industries as plasticizer. They are harmful to humans and could be carcinogenic. In this research, a new nanosorbent was prepared via a Schiff-base reaction between p-dimethylaminobenzaldehyde and Fe₃O₄@SiO₂-NH₂ nanoparticles. A characterization of the sorbent was performed by Fourier-transform infrared spectroscopy, transmission electron microscopy, scanning electron microscopy, and energy-dispersive spectroscopy. A modified nanosorbent has a core shell structure, and shows a great tendency towards the sorption of phthalate esters. Hence, it was utilized for the dispersive solid-phase extraction of six phthalate esters and determination by gas chromatography-flame ionization detection. Several variables, such as the pH, sorbent amount, salt effects, extraction and desorption time, extraction solvent type and volume, were investigated to establish the optimal conditions. Calibration graphs were linear in the range of 1.0 - 150.0 μg L^-1 for dimethyl phthalate, bis-(2-ethylhexyl) phthalate, di-n-octyl phthalate and 0.1 - 200.0 μg L^-1 for diethyl phthalate, di-n-butyl phthalate and butyl benzyl phthalate, respectively. The obtained limits of detections (S/N = 3) were in the range of 0.02 - 0.31 μg L^-1. Application of the method for the enrichment and determination of phthalate esters in mineral water, natural low fat yogurt and sodium chloride infusion (0.9%, w/v) was investigated.