What is cIEF?

cIEF stands for capillary Isoelectric Focusing. It is a high-resolution analytical technique used to separate amphoteric molecules, primarily proteins, based on their isoelectric point (pI). The separation occurs within a capillary tube filled with ampholytes, which establish a pH gradient under an electric field. Proteins migrate until they reach the pH region corresponding to their pI, where they become neutral and focused into sharp bands. cIEF is commonly used for protein characterization, quality control, and biomarker discovery due to its ability to resolve closely related protein isoforms.