Embodiments herein provide methods of purifying monoclonal and polyclonal antibodies (e.g., immunoglobulins) from biological fluids, such as cell lysates, cell supernatant and ascites fluids, using small molecule affinity chromatography. Various embodiments disclose a class of small molecules that selectively bind a nucleotide binding site that is inherent to all immunoglobulins, and in various embodiments, methods are disclosed that use one of these small molecules as a capture molecule in small molecule affinity chromatography. In some embodiments, the small molecule may be an indole, and in particular embodiments, the small molecule may be indole-3-butyric acid.