seperate sample peak from solvent front

[snee8]

What is a good way to seperate the sample peak from solvent front and retain the same peak resolution while using an ionpairing reagent in the mobile phase?

[josebenjamin]

Dear Friend,

If I understand your question you are using ion-pair chromatography and wish to enhance retention.

There are several ways to accomplish this, all involve some change in mobile phase composition. The best way perhaps is to increase the molar concentration of the ion-pair reagent, but be careful, too much may result in other difficults (precipitation, or increased retention nof non-important signals). Perhaps you should increase the concentration in 20% steps.

the other way is to decrease the % of organic components in your mobile phase. Once again perhaps a 5 to 10% decrease will show you how much you need to change this after all.

These two alternativas should give the desired results.

Good Luck

Jose benjamin

[SIELC_Tech]

What is the nature of your compound? Is it a base, acid or amino acid? Is it hydrophobic or hydrophilic neutral compound? What is your detection technique and preferable mobile phase?
If you provide more information people on this board will be able to assist you.

Regards

[snee8]

In this case the solvent front and the sample peak are coming out at the same retention time, I wish to move the sample peak to come out at a later time than the solvent front. A requirement is to keep resolution of the sample peak low, which I have now, consolidating the 5 substances in the peak as one peak.

80% Mobile Phase A:

0.01M Hexane Sulfonate
0.1M Sodium Sulfate
0.05% Acetic Acid

20% Mobile Phase B:

MeOH

Thanks

[Chris Pohl]

snee8,

Other control mechanisms in your system are ionic strenth, counterion type and ion pair reagent. You will see increased retention with less sodum sulfate. Substituting lithium sulfate will also increase retention. You will also get more retention with a more hydrophobic ion pair reagent such as octanesulfonic acid.