By Jan on Tuesday, September 9, 2003 - 06:58 am:
Dear all,
I've been looking for an LC-UV method to assay acamprosate (a small sulfonic acid) in tablets. Preferably without derivatisation. Found nothing on chemweb, scirus or google.
I believe it should be possible at 205 nm. I was thinking of starting with a 0.1% H3PO4 - acetonitrile gradient just to see if its retained on C18...
Any other suggestions ?
Thanks
By Einar Pontén - SeQuant AB on Tuesday, September 9, 2003 - 02:40 pm:
Why are you restricted to UV detection. Try Ion Chromatography and suppressed conductivity detection. That will probably also give you a different selectivty compared to constituents and other components in the matrix.
For retention of a sulfonic acid on a reversed phase column you will need an ion-pairing agent. Detection at such a low wavelength is then complicated since impurities are common in the ion-pairing reagent.
By Anonymous on Tuesday, September 9, 2003 - 02:56 pm:
High-purity ion-pair reagents that work at low UV are commercially available.
By M_Gardner on Tuesday, September 9, 2003 - 04:17 pm:
Well, I've analyzed a sulfonic acid by RP-LC (MS detection) on an endcapped C18 with nothing more than ammonium acetate for pH control. Got plenty of retention, and it didn't tail at all, although it was a little more hydrophobic than acamprosate. I'd give it a shot without the ion pair reagents first.