Recent developments in capillary isoelectric focusing with whole-column imaging detection

Capillary isoelectric focusing (CIEF) is a high resolution technique for protein separation. The on-column single point detector requires a mobilization step which lengthens the analysis time and causes an uneven resolution along the separation column. The real time and whole column imaging detection has been developed for performing CIEF without mobilization. Three types of imaging detection systems have been developed: optical absorption, refractive index gradient, and laser induced fluorescence. This technique provides a fast analysis speed (about 6 min) and a good resolution of 0.03 pH unit level. Using the absorption imaging detector, ampholyte-free IEF in tapered capillary is being demonstrated, which eliminates the interference of the expensive carrier ampholytes for protein detection in UV region. Recent advancements in this imaged CIEF technique as well as its applications are reviewed.