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    An effective and facile approach for the determination of bioactive components of Rheum ribes in the Kurdish state of Iraq and Siirt region in Turkey
    (National Library of Serbia, 2025) İbrahim Tegin; Bakhtiyar Mahmood Fattah; Mehmet Fidan; Orhan Acar; Erdal Yabalak
    Developing a streamlined and accessible method for identifying the bioactive components of Rheum ribes (rhubarb) holds significant promise in unlocking its therapeutic potential and advancing research in natural medicine. In this study, the bioactive components of rhubarb such as total phenolics and flavonoids as well as the antioxidant activity of its methanolic extract were determined. Total phenolic content was between 84.02 and 387.53 mg/L gallic acid equivalent (GAE) in extracts. Total flavonoid contents determined by the aluminium chloride colorimetric method ranged from 69.98 to 935.75 mg L-1 of routine equivalents (RE) in the extracts. The antioxidant activities were determined using ferric reducing the antioxidant potential (FRAP) and 1,1-diphenyl-2-picrylhydrazyl (DPPH) methods. In the FRAP assay, the highest antioxidant activity (IC50) was found as 25.18±0.04 mg L-1 extract. In the DPPH method, the maximum percentage inhibition was found as 88.11 %. Iron chelating activities of the samples were above 70 %. The chemical compound contents of the extracts were determined by LC-MS/MS. In this step, a total of 25 phenolic and flavonoid compounds in extracts were analysed qualitatively and quantitatively. Malic acid (15.72±0.53 mg kg-1) and rutin (76.93±0.03 mg kg-1) in the extract were identified as the major phytochemicals compounds. The results of the study confirm that rhubarb have potential biological activities and can be introduced as an important sources of natural antioxidants.
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    Cost-Effective Removal of Cu(II) and Cd(II) from Wastewater Using Walnut Shell-Immobilized Amberlite XAD-4 as a Sorbent
    (Springer Science and Business Media LLC, 2025-05-19) İbrahim Teğin; Selma Akdeniz; Gurbet Canpolat; Orhan Acar
    In this study, a cost-effective and environmentally friendly solid-phase extraction (SPE) method using walnut shell-immobilised on Amberlite XAD-4 (WNS-XAD-4) was developed to pre-concentrate and determine Cu(II) and Cd(II) ions in water samples prior to flame atomic absorption analysis (FAAS). The low-cost adsorbent, prepared by immobilizing waste walnut shells on Amberlite XAD-4 (WNS-XAD-4), was characterized using Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Thermal Gravimetric Analysis (TGA), and Brunauer-Emmett-Teller (BET) analysis. Under optimal conditions, the method achieved recoveries of 95.7% for Cu(II) and 100% for Cd(II) using 5.0 mL of 1.5 mol L-1 HNO3 as eluent. The detection limits were found as 0.582 mu g L-1 for Cu(II) and 0.03 mu g L-1 for Cd(II) with preconcentration factors of 10 and 40, respectively. The accuracy of the method was validated using the certified aquatic plant reference material BCR-670 and successfully applied to various real water samples, including those from Lake Van, Billoris Spa, tap water, salt water and wastewater from Siirt, Turkey.