Chromatography Forum

Hello,

I am developing a method for Cocoamidopropyl Betaine, so far I have achieved decent separation. My peaks are not as clean and symmetrical as I want them but I think this can be resolved using a gradient method. However, I have been reading on switching from isocratic to gradient and it's more analytical than I thought and would like some assistance on choosing a gradient for my method. I can attach the chromat if anyone would like me to. I am currently running a 70:30; MeOH:0.2% TFA as my mobile phase. Any suggestions would be greatly appreciated.

Info- run time = 30min, 1st peak ~3.2min, last peak ~23.1min running at 0.8mL/min ..Let me know if any other information is needed thanks!

Please post chromatograms, or link. I've done some work on CAP betaine myself, and maybe can help. Please list column as well.

30 minutes is a long run by our department assays...

Hello, I sent the chromatography to your email, not sure how to upload images here yet, sorry! [/img]

April - I didn't receive any E-mail from you. Please send to cussboy -at -cox.net

instructions on linking to graphics files are here:
viewtopic.php?t=2617

That said, changing a working isocratic method to a gradient is not done that often; any savings in run time are quickly chewed up by the need to re-equilibrate the column for the next injection. And peak shape improvements are often a matter of sweeping the problem under the rug. A smaller particle size / higher purity packing material might be an easier alternative.

I have a method for cocobetaine with good symmetry and separation from other products. PLease send me email inquiry.

Kind regards,

This is in response for the gradient for the CAPB… this is a 6% solution of 35% CAPB in 50:50; MeOH:.2% TFA as diluent. Method parameters are:

MP Flow-0.8 mL/min
Gas Flow- 2.6 bar
ELSD temp-90 Deg
Column- Jsphere ODS-H80 (250mm X 4.6mm, 4um)
Current Isocratic- 70:30; Methanol: .2% TFA (pH= 2.3)
20uL injection volume, run time 30 minutes

Any help would be greatly appreciated, let me know if you need any additional information.
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