2.3.2. Gel filtration using Sephadex G-25 column

The sample with the strongest Se-chelating ability obtained using ultrafiltration was weighed (100 mg), dissolved in 5 mL deionized water, filtered through a 0.2 μm membrane, and applied to a pre-equilibrated Sephadex G-25 column (100 × 2.0 cm). The peristaltic pump was set to a speed of 0.3 mL min⁻¹ and washed with deionized water. The absorbance was measured using a UV spectrophotometer at 214 nm. After determining the chelating ability of selenium, the most active fractions were mixed and lyophilized.