[RASMB] Plateaus in Absorbance?

[Ian Berke]

We had this issue for a while, always at two radial positions in every cell
and always with absorbance optics.  After replacing the whole slit assembly
didn't fix it, the technician discovered that the two screws that held the
slit on were of slightly different lengths.  He filed one down and now the
data look great!

Ian

---sent on the go....
On Jun 28, 2011 11:25 AM, "Peter Edward Prevelige Jr" <prevelig at uab.edu>
wrote:
> Hi All -
>
> We are observing what appear to be plateaus in the absorbance profile in
both equilibrium and velocity runs. The plateaus are seen with different
samples and different rotor speeds. Our current hypothesis is that the slit
in front of the detector is sticking and releasing. It appears that these
are lost steps as after the slit releases the exponential is shifted along
the radial distance axis. Some representative data is attached showing
different speeds and cells. The superimposed scans (cell 1 35K, & cell 1
44K) are scans recorded about 10 hours apart in time.
>
> Is it reasonable to think that the slit is sticking? How can we diagnose
and fix this problem?
>
> Peter
>
> Peter E. Prevelige Jr.
> Professor
> Dept. of Microbiology, BBRB 416/6
> Univ. of Alabama @ Birmingham
> 845 19th St. South
> Birmingham AL. 35294-2170
> Phone 205 975-5327
> FAX 205 975-5479
> prevelig at uab.edu<mailto:prevelig at uab.edu>
> http://www.microbio.uab.edu/faculty/prevelige/prevelige-p.htm
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://list.rasmb.org/pipermail/rasmb-rasmb.org/attachments/20110628/62466375/attachment.htm>