By Melanie on Friday, April 30, 2004 - 01:33 pm:
Hi, I am trying to develop a method for Methane sulfonic acid with UV detection.
I am using Waters ICpak Anion HR column. The problem is in the sample matrix we do have Diethylamine, which gives a broad positive peak and (1.4 min)and MSA comes out at 1.7 min as a negative peak.
Mobile phase: 3 mM Dipotassiumphthalate. If we increase the phthalate concentration, the peak shape looks bad.
Please Suggest.
Thanks and regards.
Melanie
By Chris Pohl on Friday, April 30, 2004 - 03:50 pm:
Melanie,
First off, I'm not quite sure why you're proposing to increase the phthalate concentration. If I understand you correctly, your problem is that methane sulfonate is eluting too close to diethylamine. To correct this you should dilute your eluent to increase retention or lower the pH to increase retention. Try replacing some of the dipotassium phthalate with phthalate. You may even want to try 3 mM monopotassium phthalate, although this might be too weak an eluent.
By Melanie on Monday, May 3, 2004 - 09:35 am: