چكيده لاتين
In this study, two azo-linked porous organic polymers were synthesized using polyphenol (caffeic acid) and diarylamines (benzidine and diamino diphenyl methane). The synthesized polymers were characterized by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy and energy dispersive X-ray spectroscopy (SEM-EDS), porosity and specific surface area analysis (BET), thermal analysis (TGA), X-ray diffraction (XRD) patterns, and zeta potential analysis. The porous polymer synthesized from benzidine was incorporated into melamine sponges and used as a sorbent in pipette-tip micro-solid phase extraction (PT-MSPE) for the extraction of water-soluble vitamins (B1, B2, B3, B6, B9, and B12). These vitamins were analyzed using high-performance liquid chromatography (HPLC). Optimization of synthesis parameters included the molar ratio of caffeic acid to benzidine, the amount of sodium nitrite, and synthesis time. Extraction efficiency was improved by optimizing various parameters such as the amount of sorbent, pH and ionic strength of the sample, sample volume, number of adsorption and desorption cycles, type of washing solvent, and type and volume of elution solvent. The calibration curves of B vitamins in the linear working range (50-2000 µg/L) were plotted under optimal extraction conditions. Using these curves, the coefficient of determination (R²≥0.9987), enrichment factor (1-4), limit of detection (LOD) (12-19 µg/L), and limit of quantification (LOQ) (40-63 µg/L) were obtained. The recovery of six B vitamins added to the multivitamin syrup sample ranged from 80% to 108%, with a relative standard deviation (RSD) of less than 5.4%. Finally, the optimized method was successfully used for the extraction and determination of B vitamins in multivitamin syrup and malt beverages.
In the second part of this study, a porous organic polymer synthesized from caffeic acid and diamino diphenylmethane was modified with dodecylamine to enhance its hydrophobicity. The modified polymer was characterized using the techniques mentioned above and by conducting contact angle measurements. It was then utilized as a sorbent for the extraction of fat-soluble vitamins (A, E, and D3) using effervescent tablet-assisted dispersive micro-solid-phase extraction (EA-DMSPE). The effective variables in the synthesis and modification of the polymer include the molar ratio of caffeic acid to diaminodiphenylmethane and the amounts of dicyclohexylcarbodiimide, hydroxybenzothiazole, and dodecylamine. Moreover, factors affecting the extraction process, such as the type of effervescent agent, the mass ratio of the adsorbent to the effervescent agent, the weight of the effervescent tablet, the pH of the sample solution, the type and volume of the solvent, and the optimal adsorption time, were optimized. Calibration curves were plotted in the working range of 31 to 1500 µg/L. The statistical parameters of the proposed method, including the coefficient of determination (R² ≥ 0.9983), LOD (5 to 21 µg/L), LOQ (18 to 70 µg/L), and enrichment factor (23 to 24 µg/L), were calculated. The method effectively extracted and measured fat-soluble vitamins in a multivitamin drop and an orange-flavored sports drink, achieving recoveries of 80% to 105% and a relative standard deviation (RSD) of under 5.5%.
