Chromatography Forum

So I have two issues with my HPLC methods that I'm hoping for some insight on.

1) I am analyzing some non-silicone shampoos/conditioners/personal care products to quantitate various components (generally small molecule, nonionic, nonsurfactant). I've been having issues with over pressurizing my HPLC system as (I assume) the high surfactant amounts are depositing on my ss tubing and column. I am running a MeOH/H2O gradient on a C18 column. The original sample prep was to extract in 100% water, but I've switched to an ACN extraction, diluted to an appropriate ACN/H2O solution for analysis to avoid solubilizing the surfactants. I've seen some literature on how to analyze surfactants on HPLC, but nothing on how to clean them off or avoid them altogether.

A) Is there any other known way to avoid injecting so much of the surfactants onto my system?
B) Is there a good wash method I could institute to insure the surfactants don't build up?
C) Are there any other indications that the surfactants are not depositing other than monitoring the
pressure?

2) I am also analyzing some silicone based products, but have always heard that silicones irreversibly deposit onto reversed phase columns. Again, is there any way to ensure this doesn't happen, or to clean out the column?

Thanks!

here is approach we used for injecting samples containing junk which clogs the column and interfere with analysis:
http://www.sielc.com/upload/file/pdf/SI ... r_2004.pdf

we used this for analysis of melamine in milk, amino acid in tooth paste, etc. with absolutely no sample preparation.

Extract using methanol if you can, and filter the sample solution through 0.45µ PTFE.

Extract using methanol if you can, and filter the sample solution through 0.45µ PTFE.

Why would have to switch from ACN to MeOH in order to filter through PTFE?
I'd thought PTFE is for general organic solvents.

Extract using methanol if you can, and filter the sample solution through 0.45µ PTFE.

Why would have to switch from ACN to MeOH in order to filter through PTFE?
I'd thought PTFE is for general organic solvents.

That's not why I suggested methanol. I suggested methanol as solvent for surfactant products because it's worked well for us for 30 years. Methanol-only, filter and inject.

We rarely make up samples and standards to match the mobile phase composition, not always practical.

Extract using methanol if you can, and filter the sample solution through 0.45µ PTFE.

Why would have to switch from ACN to MeOH in order to filter through PTFE?
I'd thought PTFE is for general organic solvents.

That's not why I suggested methanol. I suggested methanol as solvent for surfactant products because it's worked well for us for 30 years. Methanol-only, filter and inject.

We rarely make up samples and standards to match the mobile phase composition, not always practical.

What do you think about HPC? It is a polymer and it is the sample matrix.
I don't have much experience injecting polymers on HPLC.
But I notice constant system pressure increase after several days runs.
Not sure if it is just the column got clogged or the injector, too...

The solution for these samples are 50/50 MeCN/H2O
what do you think if MeOH would be better to dissolve them?