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Negative peaks

http://www.chromforum.org/viewtopic.php?t=24942

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Negative peaks

Posted: Wed Jun 11, 2014 9:15 pm
by pstaunton
This is just a general question about peaks that appear downward in the chromatogram of a uv detector I.e appear in the negative region of of the uv detector. Why is this?

Re: Negative peaks

Posted: Thu Jun 12, 2014 4:32 pm
by carlo.annaratone
It happens when you have a large amount of something that absorbs less than the mobile phase. I can only imagine a large amount of injection solvent maybe?

Re: Negative peaks

Posted: Fri Jun 13, 2014 12:55 am
by tom jupille
Also, occasionally with diode array detectors if the reference wavelength is set and something in your sample absorbs at that wavelength.

Re: Negative peaks

Posted: Fri Jun 20, 2014 6:09 pm
by uzman
If all the peaks going to negative , check the polarity of the cable connected to detector signal outlet.
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