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Static density gradient centrifugation; extended Hermans‐Ende equation
Author(s) -
Lechner M. Dieter
Publication year - 1997
Publication title -
macromolecular rapid communications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.348
H-Index - 154
eISSN - 1521-3927
pISSN - 1022-1336
DOI - 10.1002/marc.1997.030180905
Subject(s) - metrizamide , density gradient , polystyrene , ultracentrifuge , sedimentation , solvent , analytical chemistry (journal) , chemistry , materials science , chromatography , physics , thermodynamics , polymer , sediment , composite material , myelography , quantum mechanics , neuroscience , spinal cord , biology , paleontology , organic chemistry
An extended Hermans‐Ende equation for real solutions has been derived in order to calculate the density as a function of the radial distance in a density gradient mixture (light/heavy medium) inside an ultracentrifugal cell. The equation has been tested with equilibrium density gradient measurements of the system water/metrizamide/polystyrene latex where metrizamide is the heavy medium. The solvent compositions were 8 to 15 mass‐% metrizamide (2‐(3‐acetamido‐5‐ N ‐methylacetamido‐2,4,6‐triiodobenzamido)‐2‐deoxy‐ D ‐glucose). The latex concentration was 0.03 mass‐%. It is demonstrated that the density gradient is highly influenced due to monideality effects with respect to the solvent composition and due to the pressure gradient in the ultracentrifuge.