Microchip isoelectric focusing using a miniature scanning detection system.

A miniature scanning fluorescent detector has been developed for plastic microchannel isoelectric focusing (mIEF) analysis. The detector, comprised of a lamp and photomultiplier tube (PMT) on a moving stage, measured the real-time distribution of fluorescently labeled peptides subjected to gel-free mIEF. During the run, the effective length of the 6-cm channel was scanned every 9 s. Analysis was completed within 5 min while still obtaining high resolution and sensitivity. In addition, the scanning detector was used to characterize peptide migration properties within the channel by providing simultaneous temporal and spatial measurements.