Chromatography Forum

Hi,

I have been asked to develop an HPLC method for glycerolmonostearate (GMS) with UV and/or ESI-MS detection.

I have a validated LC/UV method for stearic acid... Not sure if it would be feasible to hydrolyse GMS to stearic acid and then use the existing method?

Or analyse GMS as it is? I suspect that GMS will have a very poor MS-response. We do not have any CAD or ELSD detectors.

I've used high temperature GC after trimethylsilyl derivatization for GMS.

I have been asked to develop an HPLC method for glycerolmonostearate (GMS) with UV and/or ESI-MS detection. We do not have any CAD or ELSD detectors.

Time for you to ask for ELSD. If high enough levels of GMS, might be able to do refractive index. I would not go the saponification route myself.

LC with an RI Detector as utilised in some of the pharmacopoieal tests for GMS works quite well, as Consumer Products Guy mentioned.

Hi,

Thanks!
We have no GC and no RI or ELSD.... Just UV and MS.

It seems as the ester bond has a similar UV-absorbance as the COOH group. And I have no problem to detect stearic acid with UV (200 nm). I will try a UV-transparent mobile phase and see if I can detect GMS with UV.

Agree that the saponification route is looking like trouble...

I tested it on my LC/UV method for stearic acid, and GMS elutes before stearic acid in that method. Seems to work fine for quantitation of GMS although the QL is about 40 µg/ml (not for trace analysis). I guess it is better than RI?

Column: XBridge C18, 3x150mm
Mobile phase: 50% ACN, 25% THF, 25% water (isocratic)
Wavelength: 200 nm