Surfactants, etc

[cstager]

I am a fresh from college chemist at a company that specializes in personal care products. We recently purchased an HPLC and are currently trying to decide what type of columns to buy. No one at my company has any HPLC experience so I thought someone here might lead me in the right direction.

We often get requests to offset various types of soaps, etc, and would like to analyze them on the HPLC to try to determine the content. I'm thinking that a normal phase column would be best? Some types of things we often work with are :

DOSS (di octyl sulpho succinate) which also contains propylene glycol, 2-ethyl hexanol, traces of dioctyl myristate, ethanol

C8-C16 amines and amine oxides

Lots of ethoxylated products (ethoxylated castor oil, decyl alcohol with 6-10 mols of EO, etc)

Many types of esters (typically C10 or longer alkyl chains, ie, ethoxylated castor oil + coconut fatty acid--->ester)

Hope this is enough to give you a good idea of what we are looking for. Any advise would be great.

[Uwe Neue]

With most of these things, I would recommend a good C18, with mobile phases approaching 100% organic or indeed 100% organic (methanol acetonitrile gradients, or 80% methanol/water to acetonitrile). Most decent columns will do.

For general applications, I recommend Symmetry C8 or C18 as the most reproducible packing that you can buy. To be honest, I need to disclose that this is my company's product, and I was involved in its development.

[Consumer Products Guy]

I am a fresh from college chemist at a company that specializes in personal care products.

A competitor, hey !!!

DOSS (di octyl sulpho succinate) can be titrated with standard cationic to dimidium bromide-disulphine blue endpoint, ASTM procedure D3049; DOSS will saponify when heated at high pH. Propylene glycol, 2-ethyl hexanol, traces of dioctyl myristate, ethanol can all be readily determined using GC.

C8-C16 amines and amine oxides: these will titrate as cationics in acid pH, see above ASTM reference.

Lots of ethoxylated products (ethoxylated castor oil, decyl alcohol with 6-10 mols of EO, etc): ethoxylated nonionics like this can be determined using high-temperature GC, or HPLC using various detectors. ELSD detector works good for these. Ethoxylated castor oil is used in a lot of solid antiperspirants.

Many types of esters (typically C10 or longer alkyl chains, ie, ethoxylated castor oil + coconut fatty acid--->ester). HPLC with ELSD detector works good for these.

[XL]

I would recommend the Acclaim Surfactant column from Dionex.

This column was specially designed for surfactants analysis, including anionics, cationics, nonionics and amphoterics. You can often separate different types of surfactants on a single column, within a same run, using the mobile phase compatibel with ELSD and MS.

Compared to suggested RP columns, Acclaim surfactant provides superior selectivity for separating different types of surfactants and far better peak shapes for cationic surfactant. I am attaching the following links that give you some proof data for this column.

1) http://www.dionex.com/en-us/webdocs/388 ... actant.pdf
2) http://www.dionex.com/en-us/webdocs/709 ... 230-01.pdf
3) http://www.dionex.com/en-us/columns-acc ... 25924.html
4) http://www.dionex.com/en-us/webdocs/258 ... et_V24.pdf


If you are interested in knowing more, please feel free to contact me.

[bhuvfe]

I agree with XL. The Acclaim Surfactant works great for many of your future analytes. It certainly works for DOSS.

[juddc]

Hey there - welcome to the club! From the sound of it, you're exactly where I was about 20 years ago.

Uwe and the others here speak the truth. For your immediate analytical needs, they sound spot-on.

Were I in your position again, I'd be inclined to go with what they suggest along with a broader selection of chemistries. Several RP chemistries (C8, C18, Phenyl or Phenylhexyl, possibly a perfluorophenyl if you're feeling funky), possibly a 300A RP for larger molecules would be a good start. Past that, I'd have a look at HILIC - lots of good stuff there lately. You can't go wrong with a good amino column...and I'm working on a HILIC separation using a silica HILIC column as I write.

Editorial content: I've never been a huge fan of RP columns with embedded polar groups because their stability has always seemed poor to me...and I'm not really enamored of 100% aqueous RP separations for a number of reasons but they do have their place.

If you haven't, I'd strongly recommend purchasing a copy of Snyder's Practical HPLC Method Development. It's been around for a while, but it's an excellent reference. I still refer to mine regularly.

There are some very interesting multimode columns out there as well that may be very useful.

Vendors that I especially like include Waters, Phenomenex, SieLC, and Imakt; all of whom make / sell good columns and suport them well. I've also had good columns from what is now Varian, but I've not purchased from there in quite a while.

Learn all you can about sample preparation, too. Cosmetic matrices can be a real challenge Darned formulators!

It may seem that I've gone off-topic a bit, but only because (from what I have seen) the personal care industry is trend driven, moves very quickly, and what you're working on this week may have little to do with what you'll need to learn in 6 months.

[aprilcparker]

I would suggest using a Acclaim Surfactant Column as well by Dionex