Determination of phthalate esters in real matrixes after extraction with a novel magnetic nano-material derived from a metal-organic framework

Herein, a magnetic nano-material derived from a metal-organic framework (MOF) of the type r-MIL-88A composite (MMIL-88A) was fabricated and utilized to extract phthalate esters in real matrixes before their determination by gas chromatography. In this way, the magnetite nanoparticles were coated with r-MIL-88A and then pyrolyzed under the nitrogen atmosphere to convert the MMIL-88A to a magnetic porous carbon (MPC). Finally, the MPC was covered with a polythiophene-polyindole (PTh-PIn) copolymer. The comparison study exhibited that MPC@PTh-PIn has the best extraction performance toward the target analytes compared with MMIL-88A, r-MIL-88A, and MPC. The synthesis of new nanomaterial was proved by FT-IR spectroscopy, XRD, scanning and transition electron microscopies, and vibrating sample magnetometry. The experimental design method was utilized to find the optimum variables. Low detection limits and wide linearity were obtained in the range of 0.06-0.08 mu g L-1 and 0.2-100 mu g L-1, respectively. The relative recovery and precision (n = 3) were achieved from 6.4% to 8.5%, and from 89% to 104%, respectively. The analytical application of the suggested method was affirmed by the preconcentration/quantification of the phthalate esters in two seawater samples satisfactorily (RSD%, 5-9%; relative recovery, 89-104%). Owing to the ion-exchange properties of PTh-PIn, the MPC@PTh-PIn can be employed for the removal/preconcentration of metal ions and anionic species in future studies.

Automated summary

A magnetic nano-material MMIL-88A was used for the extraction of phthalate esters and their determination by gas chromatography. Magnetite nanoparticles were coated with r-MIL-88A and then pyrolyzed to form a magnetic porous carbon (MPC) which was further covered with a polythiophene-polyindole (PTh-PIn) copolymer. MPC@PTh-PIn showed the best extraction performance among other materials. The synthesis of the nanomaterial was confirmed by various techniques. The method achieved low detection limits, wide linearity, and good recovery. The suggested method was successfully applied for the analysis of phthalate esters in seawater samples.