Negative peaks

Basic questions from students; resources for projects and reports.

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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?
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?
Also, occasionally with diode array detectors if the reference wavelength is set and something in your sample absorbs at that wavelength.
-- Tom Jupille
LC Resources / Separation Science Associates
tjupille@lcresources.com
+ 1 (925) 297-5374
If all the peaks going to negative , check the polarity of the cable connected to detector signal outlet.
4 posts Page 1 of 1

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