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<DIV>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?<BR></DIV>
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<DIV>-------------------------------------------------------------------<BR> Dr. John J. "Jack" Correia<BR> Department of Biochemistry<BR> University of Mississippi Medical Center<BR> 2500 North State Street<BR> Jackson, MS 39216<BR> (601) 984-1522 <BR> fax (601) 984-1501 <BR> email address: <A href="mailto:jcorreia@biochem.umsmed.edu">jcorreia@biochem.umsmed.edu</A> <BR> homepage location: <A href="http://biochemistry.umc.edu/correia.html">http://biochemistry.umc.edu/correia.html</A><BR> dept homepage location: <A href="http://biochemistry.umc.edu/">http://biochemistry.umc.edu/</A><BR>-------------------------------------------------------------------<BR> <BR> <BR></DIV>
<DIV><BR>>>> <mitrana@mail.utexas.edu> 04/05/07 11:12 AM >>><BR></DIV>
<DIV style="COLOR: #000000">Hi all<BR>I did a intensity versus wavelength scan at three radial positions - 5.8, 6.5,<BR>and 7.2 cm. At 6.5 cm, it was as I expected with a 230 nm peak (I ~ 10000<BR>units) and half that at 527 nm. However, at 5.8 cm, the 230 peak was almost<BR>zilch and only the 527 prominent. And at 7.2 cm, 230 peak had an intensity of ~<BR>13000 units and 527 half that. However, the sample and reference did not<BR>overlay. The sample intensity was virtually zero.<BR><BR>I am a little lost right now as to what is going on. Are there anymore tests I<BR>can run to identify the exact problem?<BR><BR>Mitra<BR><BR><BR>-- <BR>Mitra S. Rana<BR>Graduate Student<BR>Institute for Cellular and Molecular Biology<BR>2500 Speedway, UT-Austin<BR>Austin, TX-78712<BR>_______________________________________________<BR>RASMB mailing list<BR>RASMB@rasmb.bbri.org<BR><A href="http://rasmb.bbri.org/mailman/listinfo/rasmb">http://rasmb.bbri.org/mailman/listinfo/rasmb</A><BR></DIV></BODY></HTML>