Quantitation of zolpidem in biological fluids by electro-driven microextraction combined with HPLC-UV analysis

In this study, for the first time, an electro-driven microextraction method named electromembrane extraction combined with a simple high performance liquid chromatography and ultraviolet detection was developed and validated for the quantitation of zolpidem in biological samples. Parameters influencing electromembrane extraction were evaluated and optimized. The membrane consisted of 2-ethylhexanol immobilized in the pores of a hollow fiber. As a driving force, a 150 V electric field was applied to facilitate the analyte migration from the sample matrix to an acceptor solution through a supported liquid membrane. The pHs of donor and acceptor solutions were optimized to 6.0 and 2.0, respectively. The enrichment factor was obtained >75 within 15 minutes. The effect of carbon nanotubes (as solid nano-sorbents) on the membrane performance and EME efficiency was evaluated. The method was linear over the range of 10-1000 ng/mL for zolpidem (R2 >0.9991) with repeatability (%RSD) between 0.3 % and 7.3 % (n = 3). The limits of detection and quantitation were 3 and 10 ng/mL, respectively. The sensitivity of HPLC-UV for the determination of zolpidem was enhanced by electromembrane extraction. Finally, the method was employed for the quantitation of zolpidem in biological samples with relative recoveries in the range of 60-79 %

Removal of Cationic Dyes from Aqueous Samples Using Magnetic Gum Arabic Polymer

Introduction: The Earth's surface is covered by 75% water. However, only 3% of this water is freshwater, and just 1% of that freshwater is accessible for human consumption. In most instances, humans are responsible for introducing pollutants into water. Dyes are among the most significant pollutants found in textile wastewater. As a result of its economic feasibility and high selectivity, adsorption has gained widespread popularity as a technique for treating organic dyes. In this research, a novel magnetic adsorbent was developed and utilized to remove certain toxic dyes. Material and Methods: In this research, Gum Arabic has been utilized as a natural and biodegradable polymer for the preparation of an effective adsorbent. To enhance the surface area, efficiency and stability of this natural polymeric adsorbent, citric acid has been employed as a green crosslinker. According to our findings, ,Gum Arabic has been polymerized for the first time with citric acid as a crosslinker and utilized for the removal of cationic dyes. Additionally, a crosslinked Gum Arabic polymer synthesized using citric acid has been incorporated with magnetite nanoparticles, ensuring its facile recovery from the medium upon application of a magnetic field. Furthermore, the prepared magnetic Gum Arabic was employed for the removal of Crystal Violet (CV), Malachite Green (MG), and Methylene Blue (MB) dyes from aqueous samples. Results and Discussion: In this study, the impact of various parameters, including initial dye solution concentration, solution pH, contact time between the adsorbent and the dye solution, adsorbent dosage, and dye solution temperature, on the removal efficiency of   cationic dyes from aqueous samples was investigated. According to the results, the adsorption capacity of the adsorbent (CL-GA/Fe3O4) increased with increasing dye solution concentration, reaching maximum levels of 209.80, 205.12, and 177.12 mg/g for MB, CV, and MG, respectively. Additionally, the removal efficiency for these dyes increased with increasing solution pH, reaching 99.43% (MB), 97.13% (MG), and 96.62% (CV) at a pH of 6. Furthermore, the removal efficiency of dyes increased with increasing adsorption temperature, indicating an endothermic process. It is noteworthy that in this study, both MB and MG dyes reached their maximum removal efficiency after 20 min. In contrast, CV reached its maximum removal efficiency within a 15-min time frame. In this investigation, the Langmuir model showed a significantly better fit to the adsorption data compared to the Freundlich model, indicating its accuracy in describing monolayer adsorption. Additionally, this study revealed that the obtained adsorption kinetic data fit well with the pseudo-second-order model. This suggests that chemisorption likely plays a significant role in the rate-limiting step of the adsorption process. Conclusion: In this research, a novel nano adsorbent (CL-GA/Fe3O4) based on crosslinked Gum Arabic with citric acid and magnetized with Fe3O4 nanoparticles was employed for the removal of cationic dyes. To validate the effectiveness of the (CL-GA/Fe3O4) adsorbent, various characterization techniques, including FT-IR, FESEM, EDX, Zeta potential, and VSM, were employed. The findings of this study demonstrate the development of an innovative and efficient adsorbent for dye removal, which holds significant importance in addressing environmental challenges