Chromatography Forum

I am currently working on a formulation that contains some sodium dodecyl sulfate. I wanted to analyse the drug content in the formulation using HPLC. However I was told that SDS based formulations can negatively affect the column (not too sure how) reducing the column's lifetime. Hence I was wondering if anyone else had used an SDS based formulation in HPLC and how they tested it? i.e. is there a particular column type that needs to be used.

Some of the SDS can stick permanently to the column and then you no longer have a reversed phase column but a ion exchange column with sulfate ion as the active moiety.

Not good when you want a nice neutral column that doesn't cause tailing with bases.

Get the idea?

best wishes,

Rodney George
consultant USA

Rodney, what do you mean with "stick permanently"? Enough sticks to influence the chromatography during consecutive injection of sample, or that one can not get rid of it once injected?
I have used LiDS to clean Pinckerton and I think Inertsil columns, no changes that I could attribute to the LiDS.

It depends upon the nature of the silica used and the possible inadequate means used of 'cleaning' off the soap (SDS), Hans. Soap CAN leave a 'film', a residue which can be difficult to remove if the proper means are not utilized.

To answer your question, I suppose varying the amount of SDS in injected samples can make the retention characteristics of the column variable. I was addressing the situation of using the column for a non-SDS containing sample after using it for a sample containing SDS.

Ion-pairing reagents have been known to change the selectivity of columns in an inconsistent manner from column to column. I suppose modern columns may be affected less by these reagents and SDS than those used in the past.

Rodney George

Both posts are correct:

- With a lot of flushing, you can probably clean the (IP) from the column so
that it's back to normal, but...
- Best practice is to just dedicate that the 'IP column' for assays that use the same IP.

SDS is used a lot as a media for dissolution assays. The mobile phase I've always seen consists of 0.1% H3PO4 / organic.
I was told the 0.1% H3PO4 prevents the SDS from forming micelles (no clue if that's true).

Try a google for 'sds dissolution hplc' - it brought up some interesting links

Most of our samples contain sodium dodecyl sulfate and its ethoxylates, we inject samples with those all the time on RP18 columns, when we assay for other components.