22.1. Capillary electrophoresis Capillary electrophoresis experiments were performed on a Pro- teomelab PA 800 (Beckman Instruments Inc. Fullerton. CA system USA), equipped with a photodiode array (DAD) system that moni- tored the wavelengths between 190 nm and 400 nm. Detection was performed at 200 €10) nm. The background electrolyte (BGE) was prepared according to the following procedure: (1) a stock solu- tion (A) of sodium dihydrogen phosphate (0.1 M) was prepared by dissolving 3.0 g of NaH2PO4 in 400 ml of MQ-water and bring the final volume to 500 ml, (2) a stock solution (B) of disodium hydro- gen phosphate anhydrous (0.1 M) was made by dissolving 7.1 g of Na2HPO4 in 400 ml of MQ-water and bring the final volume to 500 ml, (3) a litter buffer was obtained by mixing A (500 ml) and B (500 ml). The pH of the phosphate buffer was measured to 7.0 (40.1). The BGE was finally prepared by mixing 50 ml buffer and 20 ml SDS (10% w/v) and bring the final volume to 100 ml with MQ-water The final concentration of SDS was thus 69 mM. A 72 cm fused silica capillary (62cm effective length) x 50 um l.D. OD. 375 um) from Polymicro Technologies, Phoenix. Az USA was used. The cap illary was cut to the desired length using a SGT Shortix capillary column cutter (Middelburg,The Netherlands) Before the first injection, the capillary was consecutively pre- conditioned with water (5 min), and 0.5 MNaoH (10 min), followed by the BGE for 10 min at 80 psi (550.7 kPa). Injections were per formed hydrodynamically at 1.0 psi (6.9 kPa) for 5 s. Immediately after the sample injection a plug of the BGE was applied with pressure at 0.5 psi (3.4 kPa) for 3 s in order to prevent sample loss due to thermal expansion after applying voltage l16]. Between the injections the capillary was washed with NaoH (0.1 M) for 5min