STRATEGIES TO IMPROVE PERFORMANCE OF CAPILLARY ISOELECTRIC-FOCUSING

Acceptance of capillary isoelectric focusing (cIEF) as a routine analy tical method has been limited by variable migration times, irreproduci ble patterns, and sample precipitation. Poor separation reproducibilit y can be traced to a number of factors. In this paper we explore the p ossibility of eliminating reagents without buffering capacity, and the use of internal markers. An often overlooked optimization stage of cI EF is mobilization. We demonstrate that hydraulic mobilization can be finely tuned by manipulating the pressure applied, and that ion additi on mobilization can be greatly improved by properly selecting the type of ion used and its concentration. By limiting the pH range of the am pholytes to 8.5 or less, hundreds of runs on an individual capillary a re possible, which is a necessity for routine analysis.