This paper examines affinity chromatography (AC) as an alternative tool for the determination of protein-ligand interactions for the particular case in which the ligand is the same protein. The methodology is less labor-intensive and more sample-efficient than traditional methods used to measure the second virial coefficient (B-22), a parameter commonly used to evaluate protein-protein interactions. The chromatographic capacity factor (k') was studied for lysozyme and equine serum albumin for a wide range of experimental solution conditions such as crystallizing agent concentration, protein concentration and pH. Parallel experiments using AC to determine k' and static light scattering (SLS) to determine B-22 showed that the two parameters were highly correlated. Two different column volumes (similar to1 and similar to0.1 mL) were tested and gave essentially the same values for k', showing the feasibility of miniaturization.