Chromatography Forum

Hi,

I enclosed a HPLC chromatogram peak.



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The sample is a crude oligonucleotide.

I was wondering:-
1) What caused the high injection peak?
2) Is there anyway I can lower the injection peak? (retention time ard 0.4mins)

I'm using the dHPLC Wavemaker.

Any inputs would be greatly appreciated.

The only way to eliminate it is to not inject a sample.

The next best way is to make sure that the sample is dissolved in the mobile phase (t0 noise essentially results from the pertubarion of the system caused by injecting a sample, The less you disturb the equilibrium, the less t0 noise you will see.

A more important question is why you would want to minimize it. It does not seem to be interfering with anything.

Most of the time my HPLC run, the injection peaks wasn't high. It was more or less occassional. It puzzles me why it happens though.

In order to answer effectively:

1. Column dimensions?

2. Flow rate?

3. Injection volume?

4. Injection solvent (sample diluent)?

5, Is every injection (samples versus calibration standards or check standards) dissolved in the same sample diluent?

Another cause of this "solvent" peak is simply an impurity that is not retained. Are you sure that there is nothing else in your sample besides the main compound?
Best,
Anna

I think another one could be that you might have a larger avoid volume in your system this time comparing to the last time. You might want to check your column connections.