At Kd = 1, solute is:
Distribution coefficient Kd reflects fractional access to internal pore volume in gel filtration. Ranging from zero to one, zero denotes complete exclusion where solute remains outside beads, one denotes complete accessibility where solute freely penetrates all pores. When Kd equals one, elution volume equals Vo + Vi, representing total liquid volume, characteristic of low molecular weight solutes like salts or small metabolites fully able to explore matrix interiors. Intermediate Kd indicates partial penetration dependent on hydrodynamic radius. Understanding full inclusion aids in choosing gels for desalting.
Ref: NCERT Biology Class XII Principles on Klenow fill-in labeling, Lehninger Chapter 9 DNA cloning techniques, and Molecular Cloning by Sambrook Chapter 10 documenting end-labeling of cohesive termini.