Analysis of Anionics Surfactants using Ion-Pair Detection

[frasmx]

Hi,

I am a chemist at a company that specializes in cleaning products. We recently purchased an HPLC with UV detector and a now I'm developing techniques to analyze anionics surfactants without any chromophoric group. I'm trying an indirect detection photometric adding an auxiliary to the mobile phase, I would appreciate help me recommend that I can use in the mobile phase to achieve this goal. thank you very much

[bhuvfe]

Frasmx,

Is ion pair a requirement? Or you can simply use this column http://www.dionex.com/en-us/webdocs/417 ... -Jul09.pdf

I never tried indirect UV but if I were you I would probably go for the column above and using a mobile phase spiked with 100-200 ppm of acetone.

Good luck.
bhuvfe

[Consumer Products Guy]

We've used HPLC-UV for anionics like sodium dodecylbenzenesulfonate. However, for stuff like sodium laureth sulfate which doesn't have good UV signal except at the "universal" lower wavelengths, UV would be tougher, like the vacancy chromatoraphy technique.

We'd lean towards HPLC-conductivity for non-UV chromaphore anionics.

Sounds like you're new to HPLC, and so is the company. Make sure your boss fully understands that you won't be successful in a week.

[Kostas Petritis]

Indirect UV detection is not that easy and you might experience what is called "system peaks" which might be quite challenging for someone not experienced.

Jacque Crommen has published several articles on the technique back in the 80's, so you might want to have a look to understand better the concept. You might want to invest in buying an evaporative light scattering detector (ELSD) for the detection of compounds without a chromophore.

[XL]

Acclaim Surfactant column is a versatile column designed for surfactant analysis, including anionics, cationics, nonionics and amphoterics. A few example separations can be found in the following link: http://www.dionex.com/en-us/products/co ... 71771.html. Although anionic surfactants can be analyzed on RP columns, the selectivity may not be be ideal for the analytes of interest to stay away from interferences, while Acclaim Surfactant column can. ELSD or CAD detector makes the method much simpler than indirect UV approach.