Assay of Quaternary Amine

[GoldLeader]

All-

I spend most of my time in the GC realm so I'd appreciate any advice you could give about my HPLC troubles:

Column = J.T. Baker, Weak Cation Exchange (WP CBx), 5 micron, 4.6x250mm
Mobile Phase = 55:20:25 :: Ammonium Chloride, pH 7.7:MeOH:ACN
Flow = 1 mL/min
Sample concentration = 0.2 mg/mL
Inj vol = 20 ul

Analyte = Quaternary amine (curare derived compound)

Problem = severe peak tailing (>2.5) of compound

What type of adjustments can I make to clean this up? Are there any other similar columns (manufacturers, etc.) out there or is this a very specialized phase?

Thanks in advance for any wisdom.
-Jeff

[Chris Pohl]

GoldLeader,

First off, I'd suggest lowering the pH. There's no need to use such a high pH with a weak cation exchange material. Lowering the pH will also help minimize any silanol interactions which could be also responsible for the tailing problem.