[RASMB] intensity issues

Borries Demeler demeler at biochem.uthscsa.edu
Thu Apr 3 11:25:01 PDT 2008


> 
> Bo,
> 
> First, what is the wavelength? If this is up in the visible that low mean
> intensity might be perfectly normal.

This was done at 280 nm with the filter off.

> Second, are you sure these folks aren't using the SedVel 60K centerpieces

This was done with the standard Beckman epon/charcoal 2-channel CPs, 
as far as I know they don't have 60k CPs.
.
> that have the lamp timing issue? That might produce an oscillation as the
> lamp timing varies slightly. The oscillation does suggest some sort of
> timing issue, so you might ask them to check whether the delay calibration
> is in a normal range (you can see it from Service...Absorbance...Cal
> Parameters).

You know, it is strange that there is such a regular variation of the intensity
with each _scan_. I would think if it is a timing issue you would see a degradation
in every scan.

> Third, regarding the low intensity, is it possible there is a problem with
> the 400 nm cutoff filter? Even if the control lever is in the right
> position, I believe the filters have been known to become detached.

Yes, good point, I'll have them check it out.

Thanks! -borries



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