Conc of Sodium lauryl sulphate in mobile phase

[prashant.pqa]

Dear All
I am developing HPLC method for very polar compound. I tried all the ways to retain this compound without ion pair reagent. But it is not retaining. I want to use the method for dissolution study purpose.
As i want to use SLS( Sodium lauryl sulphate) as ion pair reagent.
My question is how much minimum conc. of SLS should i use while developing method and how much maximum conc. of SLS i can use


Thanking you
PRASHANT

[Mark Tracy]

SLS is a very strong ion pairing agent. Try a milder one first such as hexanesulfonate or octanesulfonate. Typically the concentrations will be around 2-20 millimolar. You can fine-tune the equilibrium concentration of IP agent dissolved in the stationary phase by adjusting the organic content of the mobile phase. With SLS you will need more organic solvent to control it.

[juddc]

IP agents do work well, certainly have their place, and I've used them many times, but I would suggest that if your compound won't retain on a reverse phase column, you might do well investigate other separation modes.

For highly polar species such as urea, glycerine, sugars, niacinamide, and so forth I've had success using amino columns with acetonitrile based mobile phases. For a highly polar liganded organometalic complex I once used plain silica and a mobile phase doped with a small concentration of the ligand.

Reverse phase is fantastic, but it won't do everything.

Good luck with whatever you choose.