Ligand leakage from immunoaffinity column

With a currently used immunoaffinity chromatography method with immobilized glucagon antibodies, we experienced leakage of the ligand during repeated desorption with formic acid. The formic acid eluates contained a glucagon binder that could be identified as the glucagon antibodies, i.e. the immobilized ligand had been disrupted. Thus, our first thought that we had recovered the applied human 'big plasma glucagon' (BPG) as a carrier of glucagon proved wrong. In conclusion, caution with formic acid as chaotropic agent is advisable.