In this work, human insulin and its 6 analogues were separated and determined using CZE-MS. Three different capillaries (bare fused silica, successive multiple ionic-polymer layer (SMIL) and static linear polyacrylamide (LPA) coated) were compared based on their separation performances in their optimal operating conditions. Coated capillaries demonstrated slightly better separation of the components, although some components showed wide, distorted peaks. The highest plate number could be obtained in the SMIL capillary (192 000/m). For UV and ESI-MS detection relatively similar LOD values were obtained (0.3-1.2 mg/L and 1.0-3.4 mg/L, respectively). The application of MS detection provided useful structural information and unambiguous identification for insulins having similar or the same molecular mass. This work is considered to be important not only for the investigation of insulins but also for its potential contribution to the top-down analysis of proteins using CE-MS.
Keywords: Capillary electrophoresis; Insulin; Insulin analogues; Mass spectrometry; Therapeutics.
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