Synthesis of the magnetic composite of Ni-MOF-I in aqueous medium and its application in magnetic dispersive micro solid phase extraction of plasticizers from pharmaceutical samples

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For the first time, this research presents the synthesis procedure and analytical application of Ni-MOF-I magnetic composite. The synthesis method was green and done in an aqueous medium. The composite was employed as an adsorbent in a magnetic dispersive solid phase extraction process followed by dispersive liquid–liquid microextraction for the extraction and preconcentration of some plasticizers from pharmaceutical samples stored in plastic containers. The Ni-MOF-I magnetic composite was characterized by applying Fourier transform infrared spectrophotometry, vibrating sample magnetometry, scanning electron microscopy, energy-dispersive X-ray, X-ray diffraction, and nitrogen adsorption/desorption analyses. For operating the extraction procedure, initially, the plasticizers were adsorbed onto the adsorbent particles by vortexing. Then, the plasticizers were desorbed from the adsorbent surface using a mL volume of 2-proponal. Subsequently, the obtained eluate phase was mixed with a mixture of 1,2-dibromoethane and 1,1,2-trichloroethane and then injected into deionized water using a glass syringe. Afterward, centrifugation was done to isolate the extractant from the aqueous phase. Eventually, one microliter of the sedimented phase was injected into gas chromatography-flame ionization detection. Acceptable analytical results such as high enrichment factors (355–415) and extraction recoveries (71–83 %), low limits of quantification (0.76–1.08 μg L−1) and detection (0.23–0.33 μg L−1), wide linear ranges (1.08–300 μg L−1), and satisfactory relative standard deviation values of 4.0–6.3 % (intra-day precision, n = 5) and 4.9–7.4 % (inter-day precision, n = 5) were achieved. The suggested procedure was used as a productive analytical method based on the Ni-MOF-I magnetic composite for the extraction and determination of some plasticizers from different pharmaceutical samples filled in plastic containers. Elimination of centrifugation, using 2-propanol as a green desorption/disperser solvent, detection of di-(2-ethylhexyl) phthalate in boric acid alcohol drop, and applying µL-level of the extraction solvent are the advantages of this proposed method.