Chromatography Forum

LC Method for Diosgenin
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By Jan on Thursday, August 26, 2004 - 03:04 am:

Dear Forum members,
I have to check some nutritional supplements and cosmetic creams for the presence of DHEA (dehydroepiandrosterone) and / or diosgenin. DHEA should be no problem at just 50 % or so of acetonitrile on a C18 column (UV at 210 nm). Diosgenin, a larger steroidsaponin, seems more difficult. Does any of you have any experience with analysing diosgenin in nutraceuticals or Wild Yam (Dioscorea species) ? Preferably LC-UV.
Thanks
Jan

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By Uwe Neue on Thursday, August 26, 2004 - 03:02 pm:

What is the difficulty?

Diosgenin has almsot no UV therefore HPLC with UV detector is not a good choice. There is some early work done on HPLC determination of diosgenin and related compounds using precolumn derivatisation.

Just an update on my work (I am the original poster)
Apparently, diosgenin elutes only after about 5 minutes at 100 % acetonitrile on a 150 x2.1 mm 3 µm C18 column at 0.4 ml/min.
It can be seen at 205 nm, but the signal is weak (no real chromophore), even with ACN super gradient. I got better results with our Ion-Trap MS using positive electrospray. I find the molecular ion 415 and some in-source loss of H2O. Also MS2 and MS3 worked just fine. I am currently looking if I can get som reliable quantitative results from the MS signal. Will keep you posted.