[RASMB] Optics check

[Borries Demeler]

Mitra,

This is the check I recommend you run to make sure your optics are 
properly aligned and tuned. Your system doesn't seem to be.

If this results is obtained after cleaning the lamp and windows I would
suspect a problem with your monochromator. I think it is time to call
service. What you describe does not sound like a well-functioning machine.

-Borries
 
> 
> That was a prompt reply.
> I did the intensity scans on a windowless cell. Basically air vs. air. I haven't
> tried intensity scans on velocity mode at various wavelengths yet. In fact I am
> heading down to do this right now.
> Mitra
> 
> Quoting John Correia <jcorreia at biochem.umsmed.edu>:
> 
> > Sounds like you are doing intensity scans of real samples?  1st try intensity
> > scans in velocity mode on an empty cell at low speed (3-4K) or on an empty
> > hole, air vs air, where you scan the whole cell from 5.8 to 7.2 cm.  Vary the
> > wavelength for each scan.  Machine spec is 20% variation in linearity & is
> > done at 280 nm.   Often the intensity drops off near the top ~ 5.85 cm which
> > is a function of the alignment of the flash lamp - slight rotation can make
> > it better although not by much with the new lamp design.  This is your
> > baseline for intensity.  With a real sample vs buffer the sample will absorb
> > more light & of course they will not overlap.  The log ratio is the
> > absorbance of the sample & in your case is must be > 1.5 - 2.0 OD at that
> > wavelength?
> >
> >
> > -------------------------------------------------------------------
> >  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/
> > -------------------------------------------------------------------
> >
> >
> >
> >
> > >>> <mitrana at mail.utexas.edu> 04/05/07 11:12 AM >>>
> >
> > Hi all
> > I did a intensity versus wavelength scan at three radial positions - 5.8,
> > 6.5,
> > and 7.2 cm. At 6.5 cm, it was as I expected with a 230 nm peak (I ~ 10000
> > units) and half that at 527 nm. However, at 5.8 cm, the 230 peak was almost
> > zilch and only the 527 prominent. And at 7.2 cm, 230 peak had an intensity of
> > ~
> > 13000 units and 527 half that. However, the sample and reference did not
> > overlay. The sample intensity was virtually zero.
> >
> > I am a little lost right now as to what is going on. Are there anymore tests
> > I
> > can run to identify the exact problem?
> >
> > Mitra
> >
> >
> > --
> > Mitra S. Rana
> > Graduate Student
> > Institute for Cellular and Molecular Biology
> > 2500 Speedway, UT-Austin
> > Austin, TX-78712
> > _______________________________________________
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> > RASMB at rasmb.bbri.org
> > http://rasmb.bbri.org/mailman/listinfo/rasmb
> >
> >
> >
> 
> 
> -- 
> Mitra S. Rana
> Graduate Student
> Institute for Cellular and Molecular Biology
> 2500 Speedway, UT-Austin
> Austin, TX-78712
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