Compared to classical two-dimensional electrophoresis (2-DE) with carrier ampholytes (1,2), the advent of 2-DE with immobilized pH gradients (IPG-Dalt) (3) has produced significant improvements in 2-D electrophoretic separation with respect to:

1.	Higher resolution by using well-defined narrow-pH gradients (3).
2.	Improved reproducibility, as was demonstrated by interlaboratory comparisons (4,5).
3.	Higher loading capacity for micropreparative runs, which has accelerated spot identification by microsequencing and mass spectrometry (6–9).
4.	The possibility to resolve—under steady-state conditions—alkaline proteins, which are normally lost by the cathodic drift of carrier ampholyte focusing or separated by nonequilibrium pH gradient electrophoresis (NEPHGE) with limited reproducibility (10).