MODIFIED EXPERIMENTAL SETUP FOR SEDIMENTATION EQUILIBRIUM EXPERIMENTSWITH GELS .2. TECHNICAL DEVELOPMENTS

This part of the paper trilogy describes technical developments for an efficient experimental setup to investigate gels with equilibrium ana lytical ultracentrifugation. New 10-channel centerpieces for the Schli eren optics, a new programmable multiplexer, a modified Schlieren opti cal system, and a photo pickup with impulse transformer are introduced as major developments. Also, some new centerpieces suitable for equil ibrium experiments with solutions using the Rayleigh interference and the uv-absorption optics are presented. These centerpieces allow the i nvestigation of 10, 12, or even 26 samples per centerpiece. The proble m to find suitable materials for cell centerpieces and windows in the case of adhering samples is discussed for the system gelatin/water. A phase volume calculation for circular sample channels as a correction for the case of broadened menisci is presented. The method described a llows an accurate measurement of up to 70 samples simultaneously in an equilibrium experiment if the 8-hole rotor presented in part 1 of the trilogy is used. The number of samples is sufficient to characterize a gel/solvent system in the experimentally accessible range under iden tical conditions, which is not possible by means of any of the methods known before. All parts described are also applicable for the investi gation Of solutions. (C) 1994 Academic Press, Inc.