By Charles W. Stewart Jr. on Friday, May 12, 2000 - 11:29 am:
We are trying to develop an HPLC method for a formulation that contains Miglyol 840. While the Miglyol 840 does not have any appreciable UV absorbance at our detector wavelength (242 nm), there are several minor components/contaminants in the Miglyol 840 that do. Unfortunately, some of these components interfere with our analysis. Does anyone know what these minor components/contaminants are? Does anyone know of a way to remove these using Solid Phase Extraction (SPE)? Any other ideas would also be appreciated. Thank you.
By hinsbarlab on Tuesday, May 16, 2000 - 07:29 am:
I did a quick search on the web for Miglyol 840 but didn't find anything useful; I don't even know what the chemical structure or molecular weight is. However, RI detection is generally a good choice for compounds that don't absorb in the UV. With good control of the system, the right mobile phase and columns, etc. you can achieve detection limits around 25 - 50 ug on-column You might also want to look at Evaporative Light Scattering detectors. I've tried SPE in the past, but wasn't too happy with precision and recovery. Haven't used it since. Anybody out there ever have good luck with SPE?
Best Regards,
Michael Hinsberg
http://www.hinsbarlabs.com
By hinsbarlab on Tuesday, May 16, 2000 - 07:40 am:
Oops! Upon rereading your original post, I realized I misuderstood the question. I don't believe that my inital response was appropriate since you're not trying to analyze for Miglyol 840, but to eliminate the interferences caused by its presence. In that case, RI or ELS would probably make things worse. Sorry about that.
Best Regards,
Michael Hinsberg
http://www.hinsbarlabs.com
By Russ on Tuesday, May 16, 2000 - 12:28 pm:
My quick search led to an identity as propylene glycol dicaprylate / dicaprate. Are you sure the small peaks are impurities and not the main components that just appear small due to low absorbance at your wavelength? Have you tried Miglyol 840 at a lower wavelength (220) to see where the components are actually eluting? Can't really offer much in the way of suggestions without knowing more about your method (column, mobile phase) and analyte. Assuming a reverse phase method, have you tried different organic mobile phase component(s), pH, or bonded phases?
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