Glycerolmonostearate by HPLC?

[Mattias]

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.

[Consumer Products Guy]

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.

[AaronAIT]

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

[Mattias]

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...

[Mattias]

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

[Mattias]