Polyaniline (PAni), cellulose fiber (CF) and a PAni–CF composite, which were characterized by infrared spectroscopy, scanning electron microscopy and thermogravimetry, were investigated in adsorption studies of meloxicam (MLX) from aqueous media.
Understanding the adsorption mechanisms of drugs on the surfaces of solid materials is important for determining the fate of these compounds in aqueous samples as water or wastewater treatment. A composite based on polyaniline (PAni), polypyrrole (PPy) and cigarette filters (CFs), PAni-PPy-CFs, was prepared, characterized by FTIR, TGA and SEM and applied in investigation of adsorption of a non-steroidal anti-inflammatory, phenylbutazone (PBZ), from aqueous solutions. A batch of experiments were conducted and four kinetic models and five isotherms models were used to describe the adsorption process. The experimental kinetic data were fitted very well with the second-order kinetic model, indicating that PBZ adsorption involves chemical adsorption in different binding sites, which could control the reaction rate. The equilibrium adsorption data were best fitted with the dual-site Langmuir-Freundlich isotherm, with maximum adsorption capacity of 100.22 mg g -1 , which recognizes the existence of two kinds of adsorption sites on the polymer composite surface. Finally, this composite might act as excellent adsorbents for environmental and analytical processes, for example, stationary phases in separation processes.
In this work, we developed a HPLC method for the multidetermination of avermectins (AVM) (abamectin-ABA 1b and ABA 1a, eprinomectin-EPR, and ivermectin-IVM) and milbemycins (moxidectin-MOX) in milk samples using polypyrrole (PPy) as adsorbent material in pipette-tip solid-phase extraction (PT-PPy-SPE). PPy was characterized by scanning electron microscopy, thermogravimetric analysis, Fourier transform infrared spectroscopy, and X-ray diffraction and the data agreed with the literature. The sample preparation included the clean-up of the milk by protein precipitation (PP) with acetonitrile and extraction of the analytes by PT-PPy-SPE. The chromatographic method was developed in reverse phase and isocratic mode with flow rate at 1.2 mL min and ultraviolet detection at 250 nm. The mobile phase composition was acetonitrile:methanol:water (55:25:20, v/v/v). The studied parameters and the optimized conditions for the sample preparation were washing solvent (300 μL water), volume and type of eluent (500 μL methanol), volume and pH of sample (1 mL and pH 10), amount of adsorbent material (50 mg PPy), and without addition of salt (NaCl). The method was linear over the concentration range from 20 to 3000 ng mL with coefficients of correlation (r) ≥ 0.99 for all analytes and recoveries around 100%. The method developed and validated was used for the analyses of real milk samples from cow treated with Ivomec (IVM 3.5%), in which were found 21.51 ± 2.94 ng mL of IVM. Finally, the results proved that PT-PPy-SPE coupled to HPLC-UV was economical, simple, and easy-to-perform technique. Graphical abstract Pipette-tip solid phase extraction using polypirrole as adsorbent material for determination of avermectins and milbemycins in milk.
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