Preparation of density gradient solutions
Exposure (several months) of iodixanol solutions to direct sunlight will cause a slow release of iodine (solution turns yellow); OptiPrep should therefore be stored away from strong sunlight.
On standing, iodixanol may "settle out" of concentrated solutions, which should be well mixed before use. 3. Osmolality The observed osmolality of OptiPrep depends on the mode of measurement (vapour pressure or freezing point); moreover the situation is complicated by the tendency of the iodixanol molecules to associate non-covalently in a concentrated aqueous solution.
Measured values for its osmolality are
thus lower than might be expected. Importantly however, when OptiPrep is diluted with a buffered
isoosmotic solution, the iodixanol oligomers dissociate and all dilutions are isoosmotic. Under normal
operating conditions therefore OptiPrep behaves as if it had an osmolality of approx 290 mOsm.