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Peaks separation

Posted: Mon Mar 18, 2019 2:19 pm
by Dr.Malik
what is the expected reasons for no separation of peaks of antibiotics on lc-msms all peaks almost appear close to each other

Re: Peaks separation

Posted: Mon Mar 18, 2019 5:04 pm
by Murshad
If components have similar or very slightly different affinity for phases (mobile and stationary) then there will be almost no difference.
In case of LCMS e/m also comes into game.


Re: Peaks separation

Posted: Mon Mar 18, 2019 8:33 pm
by HPLC chemist
Try adding a 3rd solvent to your mobile phases, that is discriminatory. There are very few molecules that have a similar solubility in three solvents. Use a slow gradient ramp around these peaks.

Re: Peaks separation

Posted: Wed Mar 20, 2019 8:27 pm
by Vlad Orlovsky
What are your compounds? Usually antibiotics have a charge and mixed-mode chromatography is exploring small difference in ionic and hydrophobic properties of the molecule. In my 17 years using mixed-mode columns I only had one or two cases when compounds were not FULLY resolved. Let me know if I can help. Send me an email trough our website.