High-performance liquid chromatography of iodine-labeled insulin and glucagon derivatives with on-line...

Insulin and glucagon were labeled with iodine. The reaction products were analyzed by high-performance liquid chromatography. It is shown that the pH of the reaction medium has a large effect on the position and the degree of iodine substitution as well as on the oxidation of the Met-containing glucagon and, furthermore, that the molar ratio of iodine to polypeptide hormone used during the labeling procedure affects not only the amount of iodine incorporated but also the distribution of iodinated products. The results show that certain iodinated derivatives are separated from each other and from the respective unlabeled polypeptide and thus can be obtained in a pure state.