In-tube stir bar sorptive extraction based on 3-aminopropyl triethoxysilane surface-modified Ce-doped ZnAl layered double hydroxide thin film for determination of nonsteroidal anti-inflammatory drugs in saliva samples.

A thin-film based on 3-aminopropyl triethoxysilane surface-modified Ce-doped zinc-aluminum layered double hydroxide was synthesized on the inner surface of an aluminum tube. It has been applied to in-tube stir bar sorptive extraction of nonsteroidal anti-inflammatory drugs in saliva samples followed by high-performance liquid chromatography. The sorbent was characterized by scanning electron microscopy, X-ray diffraction, Fourier-transform infrared spectroscopy, energy-dispersive X-ray spectroscopy, and elemental mapping. The extraction parameters including sample pH (4.2), extraction time (10 min), stirring speed (800 rpm), type of eluent (acidified tetrahydrofuran), eluent volume (100 µL), and desorption time (6 min) were thoroughly optimized. Under the optimum conditions, limits of detection were found to be less than 5.0 ng mL-1. Calibration plots were linear within the range 10-1000 ng mL-1 (R2 > 0.9982). Absolute recoveries were calculated in the range 63.5 to 72.4%. The repeatability (intra- and inter-day precision) and reproducibility (tube-to-tube precision) at concentrations of 50, 250, and 500 ng mL-1 were less than 7.6% and 9.4%, respectively. The method accuracy based on the relative error was calculated at these concentrations and ranged from - 4.9 to - 9.3% for intra-day relative error (%) and - 6.8 to - 11% for inter-day relative error (%). Finally, the method applicability was examined for the determination of nonsteroidal anti-inflammatory drugs in saliva samples, and good relative recoveries were obtained within the range 86.5 to 95.2%. As a result, the introduced method can be applied as a suitable alternative to measuring nonsteroidal anti-inflammatory drugs in biological fluids. Graphical abstract A surface-modified Ce-doped ZnAl LDH thin film was synthesized on the inner surface of an Al tube and applied for in-tube stir bar sorptive extraction of NSAIDs in saliva.

Synthesis and characterization of polyamide-graphene oxide-polypyrrole electrospun nanofibers for spin-column micro solid phase extraction of parabens in milk samples.

In the present study, an electrospun composite of polyamide-graphene oxide-polypyrrole was synthesized. The characterization of the synthesized material was accomplished using field emission scanning electron microscopy (FESEM) and Fourier transform infrared spectroscopy (FT-IR). FESEM images showed uniform and beadles nanofibers. The composite was employed as a novel sorbent for spin-column micro solid phase extraction to determine parabens in milk samples. Addition of graphene oxide and polypyrrole into the polymeric network of polyamide significantly improves the extraction efficiency of the electrospun sorbent due to providing the possibility of various interactions with the target analytes such as hydrogen bonding, hydrophobic and π-π stacking. All effective parameters on the efficiency of both adsorption and desorption steps were optimized. These parameters were pH of sample solution (5.0), sorbent amount (20 mg), type and volume of desorption solvent (200 µL of methanol), number of cycles (7 and 14) and centrifugation speed (600 and 500 rpm) of both adsorption and desorption steps. Under the optimal conditions, the calibration plots were linear within the range of 10-1000, 15-1000, and 20-1000 ng mL-1 for methyl paraben, ethyl paraben and propyl paraben, respectively. Limits of detection were obtained lower than 7.0 ng mL-1 by HPLC-UV. Intra- and inter-assay relative standard deviations were less than 8.6% and 5.8%, respectively. Finally, the method was successfully applied for determination of parabens in some milk samples and good recoveries were obtained within the range of 81.7-97.8%. The results demonstrated good efficiency of the synthesized electrospun composite nanofibers as the packing material for spin-column micro solid phase extraction.

Polypyrrole-coated magnetic nanoparticles as an efficient adsorbent for RB19 synthetic textile dye: Removal and kinetic study.

The present work deals with the first attempt to study the removal of synthetic textile dye, reactive blue 19 (RB19), using the magnetic Fe3O4 nanoparticles modified by pyrrole (PPy@Fe3O4 MNPs) as an efficient adsorbent. The nanoadsorbent was synthesized using chemical co-precipitation. Scanning electron microscopy and FT-IR were used to characterize nanoparticles. Factors affecting the dye adsorption including the pH of the dye solution, amount of adsorbent and contact time were also further investigated. Sorption of the RB19 on PPy@Fe3O4 MNPs reached to equilibrium at contact time less than 10 min and fitted well to the Langmuir adsorption model with a maximum adsorption capacity of 112.36 mg g(-1). Experiments for adsorption kinetic were carried out and the data fitted well according to a pseudo-second-order kinetic model. Moreover, the MNPs were recovered with over than 90% efficiency using methanol as elution agent.