Dioctyl sodium sulfosuccinate

[Zahed]

I'd like to determine Dioctyl sodium sulfosuccinate(C20H37NaO7S), it often referred to as docusate sodium, Aerosol OT or AOT. I could not find any test method our procedure. Would you please let me know which detector in HPLC is better for measurement of AOT?

[XL]

Several methods can potentially be used, such as LC-MS (at least low ppb), LC-Conductivity (~10 ppb and good selectivity), LC-CAD (~1 ppm) or ELSD (~5-10 ppm), LC-UV (10 - 50 ppm). The sensitivity levels are only estimations to show relative sensisity between different detection methods. The separation column can be a reversed-phase column (e.g. C18) or a specialty column (e.g. Acclaim Surfactant column from Dionex). Can you tell provide some information on the sample matrix, sensitivity requirements, and what instrument available to you?

[Mattias]

There is an LC method for Docusate Sodium in USP. It runs with UV at 210 nm.

I have run this substance myself on LC, and it gives a lot of tailing using standard column and no additives to the mobile phase. You more or less have to run a fast gradient to get a decent peak shape. I assume that some triethylamine in the mobile phase could make wonders, or a negatively charged column surface (such as Primesep 100) - but I have not tested this myself. UV should be fine though, if you are not looking at trace levels.

[Madlen]

Hi everyone,
I have a problem with determination of docusate sodium. I tested USP method, but the separation was not good.
USP:
Mobile phase: alcohol:water (78:22)
column: C18 5μm RP
column temp.: 30oC
Flow rate: 1mL/min
UV detection. at 210nm.
I also used ACN: ammonium acetate 7mM (80:20) as a mobile phase (column temp. 40oC, flow rate 0,7-1ml/min), but it was not good too. Next I used ACN: acetic acid 2% and I didn’t get a peak after injecting my standard of docusate sodium after 60 minutes….
Can someone help me to set up another method or give me advices to make the current method more optimal? Thanks a lot.

[Consumer Products Guy]

Again: this all depends upon your requirements, and your sample matrix. And whether or not this is regulated, like a pharmaceutical.

To the extremes: if you had 10% in water, you could assay by drying. If you you have 100 ppm in a cleaning validation sample, tons different.