CAPILLARY ISOELECTRIC-FOCUSING WITH IMAGING DETECTION

A simple on-line absorbance imaging detection system was constructed f or detection of capillary isoelectric focusing (CIEF). Because of the use of the CIEF-imaging detection system, separation and detection of protein sample could be completed in 2 minutes. The use of the imaging detection system also allowed for studying the focusing process. When a 4 cm long, 200-mum i. d. square capillary was used as the separatio n column, the concentration detection limit of the detector reached 5 mug/Ml. This is the first report of applying absorbance imaging detect ion system to capillary electrophoretic techniques. The absorbance ima ging detection system was compared with the refractive index gradient imaging detection system. For the capillary with large i. d., the abso rbance imaging system showed higher sensitivity than the refractive in dex gradient imaging detector. However, the refractive index gradient imaging system was more suitable for narrow capillaries because it app lied a laser as the light source which could be easily focused into na rrow capillaries. The sensitivity of the refractive index gradient ima ging detector was expected to be higher for narrower capillaries than the absorbance imaging detector.