[RASMB] floatation and sedim.

[Ariel Lustig]

Dear  Christine, dear Colleagues,
it may be, that in  your  case you   have  to  work  in a D2O - buffer, where the  sed.velocity me  be reduced
due  to  higher  solvent  density but  the floataion may increase. Sure one  have to try  different  densities 
where  you may  catch  both  fractions  in the  same  run or to catch one out of the field.
 Apro-pos the different densities may help you 
for the determination of the density dependent fractions (seeC H  Huang and J Charlton  (JBC 1971  vol 216  8  April )  If you speak about  purification  I understand that you intend to separate preparativly
some  fractions. At this point  I like  to mention  that  they are  Vertical rotors where  the tubes have approximately the same  diameter  as an UC cell.so , if you  have  the run-condition , speed  and  time 
of  the  analytical run,  you  can copy this  condition for  the   vertical rotor. When the  rotor  stands  still the   fractions (bands) became  horizontal and easy to suck them out.
I agree 100 % with Kristian Schillig about the   schlieren-peak  inside  the   abs.phenomena, but  this  knowledge  will not  help to separate  or determe  this  two  different moving  boundariesbut to recgnize them. 
good  luck  Christine.....ariel
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