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Author Topic: odd feature in HPLC  (Read 72 times)

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mjc123

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odd feature in HPLC
« on: Today at 02:42:48 AM »

Can anybody explain the scoop-shaped negative feature at the beginning of the chromatogram?
(Reverse phase HPLC, acetonitrile 1 mL/min, sample dissolved in acetonitrile, DAD detection at 210 nm.)
The feature does not appear when running a solvent blank, but does not seem to be a component of the sample because (i) there is no corresponding feature in the RI signal, (ii) its magnitude does not vary with injection volume.
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Corribus

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Re: odd feature in HPLC
« Reply #1 on: Today at 04:14:10 AM »

No HPLC expert by any means, but what happens if you just inject a blank (some of the mobile phase)- do you still see the anomaly? Interestingly, it doesn't look like a peak, per se, just a broad negative region.

If you don't get any help here, you might try the chromatography forums.

http://www.chromforum.org/
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DrCMS

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Re: odd feature in HPLC
« Reply #2 on: Today at 05:43:39 AM »

It appears the solvent used to dissolve the sample has a lower absorbance at 210nm than the HPLC solvent.

Are the HPLC solvent and the solvent used for the sample prep exactly the same grade?  From the same bottle?
Is the HPLC solvent eluting from the end of the column recycled or discarded?
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