Electrospun mesh pattern of polyvinyl alcohol/zirconium-based metal-organic framework nanocomposite as a sorbent for extraction of phthalate esters.

Herein, an electrospun composite polyvinyl alcohol/zirconium-based metal-organic frameworks (PVA@UiO-66) nanofiber coating was prepared on the surface of stainless steel mesh (SSM) and then utilized as novel sorbent for the extraction of phthalate esters (PEs) in milk and water samples. Gas chromatography equipped with a flame ionization detector (GC-FID) was used for the quantitative determination of extracted analytes. The SSM coated with PVA@UiO-66 was used in a polypropylene syringe to fabricate the solid-phase extraction (SPE) device. The PVA@UiO-66 nanofiber coating was confirmed using X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy analysis (FT-IR), and field emission scanning electron microscopy (FESEM). The effective parameters of the extraction efficiency including volume and type of desorption solvent, sample volume, ionic strength, pH, extraction flow rate, and desorption flow rate were optimized. At the optimal extraction conditions, the calibration plots for phthalate esters were linear within the range of 0.05-100 ng mL-1 and, low detection limits (0.015-0.06 ng mL-1). Finally, this semi-automated SPE was used for the extraction and detection of phthalate esters (PEs) in milk and various environmental real water samples. The results showed good precision with acceptable and satisfactory extraction recovery values ranging from 89.5 to 99.2% and relative standard deviations (RSDs%) ranging from 4.5 to 6.9%.

Synthesis of a zinc-based metal-organic framework with histamine as an organic linker for the dispersive solid-phase extraction of organophosphorus pesticides in water and fruit juice samples.

As a highly efficient adsorbent, the zinc-based metal-organic framework has been successfully synthesized from zinc as the metal ion and histamine as an organic linker under solvothermal conditions. The structure of nanocomposite was characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier transform infrared (FTIR) analysis. The synthesized sorbent was applied for dispersive solid-phase extraction (DSPE) of organophosphorus pesticides (OPPs) in fruit juice and water samples. The gas chromatography-flame ionization detector (GC-FID) was used as instrument detection. The main experimental factors affecting the extraction efficiency such as the desorption conditions, sorbent amount and extraction time were evaluated and optimized. Good linearity exhibited for all of the target analytes in the 0.1-100 ng mL-1 concentration range. The enrichment factors (EFs) ranged from 803 to 914. The limits of detection (LODs) for the established DSPE-GC-FID method were found to be 0.03-0.21 ng mL-1. The DSPE-GC-FID method can be used for the analysis of OPPs in water and fruit juice samples with recoveries of the analytes in the range of 91.9% to 99.5%.

Magnetic solid-phase extraction of polycyclic aromatic hydrocarbons in water samples by Fe3 O4 @polypyrrole/carbon nanotubes.

A magnetic solid-phase extraction method coupled with gas chromatography was proposed for the determination of polycyclic aromatic hydrocarbons in the environmental water samples. The magnetic adsorbent was prepared by incorporating Fe3 O4 nanoparticles, multi-walled carbon nanotubes, and polypyrrole. The main factors affecting the extraction efficiency including the amount of the sorbents, desorption conditions, extraction time, salt concentration, and sample solution pH were investigated and optimized. Under the optimum conditions, good linearity was obtained within the range of 0.03-100 ng/mL for all analytes, with correlation coefficients ranging from 0.9942 to 0.9973. The method detection limits (S/N = 3) were in the range of 0.01-0.04 ng/mL and the limits of quantification (S/N = 10) were 0.03-0.1 ng/mL. Repeatability of the method was assessed through five consecutive extractions of independently prepared solutions at concentrations of 0.1, 10, and 100 ng/mL of the compounds. The observed repeatability ranged 3.4-10.9% depending of the compound considered. The proposed method was successfully applied in the analysis of PAHs in environmental samples (tap, well, river, and wastewater). The recoveries of the method ranged between 93.4 and 99.0%. The procedure proved to be efficient and environmentally friendly.