Practice question

Sephadex is cross-linked dextran gel classified by G-value indicating degree of cross-linking and porosity. G-50 denotes moderate cross-linking with fractionation range for globular proteins approximately 1,500 to 30,000 daltons. Molecules larger than 30,000 daltons are excluded, eluting at void volume; smaller molecules penetrate and are retarded. Exclusion limit defines upper molecular weight threshold. Different grades like G-25, G-75, G-100 offer varying ranges. Knowledge of exclusion limits guides selection for desalting, buffer exchange, or separation of peptides from proteins, ensuring desired analyte falls within fractionation range for effective resolution.