Polypyrrole as Adsorbent in Magnetic Solid Phase Extraction for Progesterone Determination from Human Plasma

A straightforward and effective chromatographic method has been created for the analysis of progesterone from human plasma using a composite based on polypyrrole/magnetic nanoparticles in the sample preparation procedure. The quantification of progesterone is necessary due to its importance in human development and fertility. The employed conditions used acetonitrile:ultrapure water (70:30, v/v) as the mobile phase at 1.0 mL min-1 and an octadecyl silane column (Phenomenex Gemini, 250 mm × 4.6 mm, 5 μm) at a wavelength of 235 nm. The composite and its precursors were synthesized and properly characterized by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy/energy dispersive spectroscopy, thermogravimetric analysis, and point of zero charge. The main factors affecting the extraction recovery of progesterone from pool human plasma samples employing magnetic solid phase extraction have been studied, such as sample pH (without adjustment), sample volume (1000 μL), washing solvent (ultrapure water), eluent (acetonitrile), eluent volume (1000 μL), and amount of adsorbent (10 mg). The extraction recoveries ranged from 98% to 102%, and linearity ranged from 5 to 3000 ng mL-1. The correlation coefficient (r) was ≥0.99, and acceptable relative standard deviation (precision), relative error (accuracy), and p-values (robustness) were observed. Lastly, the plasma samples from pregnant women were successfully analyzed by the validated method.

Efficient and selective extraction of azamethiphos and chlorpyrifos residues from mineral water and grape samples using magnetic mesoporous molecularly imprinted polymer

A magnetic mesoporous molecularly imprinted polymers was synthesized on the surface of magnetic nanoparticles silanized with 3-(trimethoxysilyl) propyl methacrylate to introduce reactive methacrylate groups. Subsequently, methacrylic acid monomers were grafted onto the surface of this adsorbent functionalized via polymerization by precipitation. Magnetic mesoporous molecularly imprinted polymer was properly characterized by different techniques and applied as adsorbent in magnetic solid phase extraction for selective determination of two organophosphorus pesticides, azamethiphos and chlorpyrifos, in mineral water and grape samples. After sample preparation optimization, recoveries of 99.56% and 98.86% were obtained for azamethiphos and chlorpyrifos, respectively. The magnetic solid phase extraction coupled to HPLC-UV presented limit of quantification of 5 ng mL^-1, linearity ranged of 5 to 1000 ng mL^-1, in addition to adequate accuracy, precision and robustness. The pesticides showed stability in the matrix and were satisfactorily quantified in real mineral water and grape samples.

Synthesis of mesoporous magnetic polypyrrole and its application in studies of removal of acidic, neutral, and basic pharmaceuticals from aqueous medium

As an alternative to traditional adsorbents, mesoporous magnetic polypyrrole (MMPPy) was first used as an adsorbent for the removal of acid, neutral, and basic pharmaceutical compounds considered aqueous pollutants. Ibuprofen (IBU, acid), caffeine (CAF, neutral), and bupropion (BUP, basic) were chosen as adsorbates and applied in adsorption studies. They proved to be pH dependent of the aqueous solution and the best results were found at pH 4 for IBU and CAF and pH 7 for BUP and 60 mg was the optimal amount of adsorbent to be used in the studies. Adsorption was extremely fast and the equilibrium was reached up to 180 s. The adsorption data of all analytes could be well interpreted by the pseudo second-order kinetic model and the dual-site Langmuir-Freundlich isotherm model. The adsorption capacities obtained by the dual-site Langmuir-Freundlich model were 53.67 mg g^-1, 16.74 mg g^-1, and 24.72 mg g^-1 for IBU, CAF, and BUP, respectively. Thermodynamic parameters revealed that IBU adsorption becomes spontaneous as temperature increases and CAF and BUP adsorption occurs through a non-spontaneous process. In addition, this study shows endothermic nature of the adsorption process. Analytes were desorbed using an aqueous solution at pH 10 for IBU, pH 7 for CAF, and pH 4 for BUP and then the material was regenerated successfully. The results suggest that MMPPy can be efficiently used in the removal of different organic analytes found in contaminated water.

Magnetic molecularly imprinted conducting polymer for determination of praziquantel enantiomers in milk

A new selective adsorbent based on magnetic molecularly imprinted conducting polymer was firstly synthetized and applied to the magnetic solid phase extraction (MSPE) for the determination of PZQ enantiomers in milk samples.

Synthesis and characterization of polyaniline, polypyrrole and zero-valent iron-based materials for the adsorptive and oxidative removal of bisphenol-A from aqueous solution

One pot synthesis of a polypyrrole, polyaniline and Fe0 nano-composite (Fe0-PPY/PANI) was achieved by polymerizing aniline and pyrrole with FeCl3 followed by the reduction of Fe3+ to Fe0 with NaBH4. PPY/PANI was synthesized the same way as Fe0-PPY/PANI, except that all the FeCl3 was removed by rinsing. The presence of Fe0 was demonstrated using several analytical techniques; this was shown in comparison to materials that are without Fe0. A series of materials were screened as both adsorbents and catalyst for the activation of H2O2 towards bisphenol A (BPA) removal in batch experiments. Polymers performed better than composites containing Fe0 at adsorption, whereas Fe0 based materials were better catalysts for the activation of H2O2. BPA samples were then spiked with other contaminants including sewage water to test the performance of the various adsorbents and Fenton catalysts. PPY/PANI was found to be a better adsorbent than the rest, whereas Fe0-PPY/PANI was the best Fenton catalyst. The adsorption kinetics of BPA onto PPY/PANI was studied; it was found that the process was governed by the pseudo-second-order kinetic model. The adsorption isotherms revealed that the amount of BPA taken up by PPY/PANI increased with increasing temperature and was governed by the Langmuir adsorption isotherm. The mechanism in which Fe0-PPY/PANI and H2O2 degraded BPA was studied, it was found that surface-bound hydroxyl radicals were responsible for the degradation of BPA. It was also shown that the degradation process included the formation of smaller compounds leading to the reduction of the total organic content by 57%.