[RASMB] Optics check
mitrana at mail.utexas.edu
mitrana at mail.utexas.edu
Thu Apr 5 09:43:27 PDT 2007
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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>
>
>
--
Mitra S. Rana
Graduate Student
Institute for Cellular and Molecular Biology
2500 Speedway, UT-Austin
Austin, TX-78712
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