[RASMB] peculiar leakage problem!

[John Correia]

How do you torque your cells?  At least three times until they don't slip.  I usually push the tension a bit to 140 with each push.  I mostly use newer centerpieces now, mostly SedVel50K or SedVel60K, occasionally 3 mm Beckman centerpieces, without leakage.  Most leaks occur during acceleration or deceleration and not during constant spinning - until the catastrophe of a full failure occurs.  The classic cause of leaks is dust or finger prints on the window face/centerpiece surface so blow off windows and centerpieces during assembly.  50K is above the Beckman centerpiece limits, although many people have always ignored those limits.  Not sure if that is an issue for leaks.
 
A consistent leak problem can be wear on the surfaces, scratches or aging.  You can polish them on glass surfaces to recover the flat seal, figure 8 patterns with a soapy solution.  Camis I think will do it for you for a fee - they have a machine that does it.
 
You also didn't say what the material is.  I presume they are not softer material which at 50K would deform and leaks for ever.
 
-------------------------------------------------------------------
Dr. John J. "Jack" Correia
Department of Biochemistry
University of Mississippi Medical Center
2500 North State Street
Jackson, MS  39216
(601) 984-1522                                 
fax (601) 984-1501                             
email address: jcorreia at biochem.umsmed.edu     
homepage location: http://biochemistry.umc.edu/correia.html 
dept homepage location:    http://biochemistry.umc.edu/ 
-------------------------------------------------------------------




>>> On 6/12/2009 at 3:51 PM, in message <3c702e160906121351p204e0820kd1b9ec04f9efc189 at mail.gmail.com>, sumit goswami <ikant11 at gmail.com> wrote:
Dear all
we have been trying do some sed-velocity experiments for last couple of weeks but every time we tried most of the cell assemblies leaked!! Apparently it seemed like a simple problem of aging of center pieces but then very recently I ran all the seven cell assemblies overnight at 50000rpm with water in them and none leaked! After that I used the same set of assembly for running my sample by sucking off the water from them and 4 out of 5 leaked even at 4000rpm. We have used different kinds of buffer so far... PE (5mM Na-phosphate, 1mM EDTA), TE (10mM Tris, 1mM EDTA), Poly buffer (MES,tris, acetate). All of our buffer had 0.01%PEG in them. We have tried both PH 5 & 8.
Can anyone suggest what's going on? We are ready to buy new centerpiece but not sure if that's the problem. The result with water is confusing us!
Thank you very much!
Regards,
Sumit 


Individuals who have received this information in error or are not authorized to receive it must promptly return or dispose of the information and notify the sender. Those individuals are hereby notified that they are strictly prohibited from reviewing, forwarding, printing, copying, distributing or using this information in any way.

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://list.rasmb.org/pipermail/rasmb-rasmb.org/attachments/20090612/4add8f59/attachment-0001.html>