[RASMB] Re: peculiar leakage problem!

[sumit goswami]

For sure I put the cell inside the rotor with the holes facing towards the
axis of rotation. But I am not exactly sure if the leakage occured through
the feeling hole or between the centerpiece and windows. I have seen spots
of dried sample on the ouside surface of windows but I don't remember seeing
any circular line at the wall of the centrifuge chamber. I have seen marks
of leaked sample at the bottom of the rotor where it supports the cell. So
in my understanding it is very likely that the leakage has occured between
the windows and the centerprice. One thing I must have to say is that our
centerpices are old and they might have some scratches or damages that are
not clearly visible through naked eyes. As Dr. Philo mentioned it might be
that in presence of protein the surface tension of the sample became low
enough to leak through the defects of the centeriece

On Fri, Jun 12, 2009 at 4:51 PM, 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
>
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