Application of an MOF-based dispersive micro solid phase extraction method followed by dispersive liquid–liquid microextraction for plasticizers’ detection and determination

Abstract

The current study aims at the extraction and preconcentration of some plasticizers, including dimethyl phthalate, diethyl phthalate, di-iso-butyl phthalate, di-n-butyl phthalate, di-(2-ethylhexyl) adipate, and di-iso-octyl phthalate, migrated into different samples (mineral water, injection serum, orange juice, and carbonated soft drink) using MIL-68 (Al) in a dispersive micro solid phase extraction method prior to dispersive liquid–liquid microextraction. The sorbent was characterized using X-ray diffraction, Fourier transform infrared spectrophotometry, nitrogen adsorption/desorption, scanning electron microscopy, and energy dispersive X-ray analyses. At first, the analytes are adsorbed on MIL-68 (Al) from a solution with dissolved Na₂SO₄. Then, the sorbent particles are separated from the aqueous medium by centrifugation. Methanol is utilized as an elution solvent to desorb the plasticizers from the sorbent. Then, the eluent is mixed with carbon tetrachloride at the μL-level and injected into an aqueous solution containing dissolved Na₂SO₄. The obtained cloudy solution is centrifuged and an adequate sedimented extractant is injected into the gas chromatograph equipped with a flame ionization detector. Satisfying figures of merit including high extraction recoveries (50–93%) and enrichment factors (251–466), wide linear ranges of the calibration curves, and low limits of detection (0.63–1.86 μg L⁻¹) and quantification (2.08–6.14 μg L⁻¹) were achieved in the present approach. In addition, a small consumption amount of the sorbent and organic solvents were the highlights of the developed method.