assay glycerol

[Robert Brightman]

Does anyone have an HPLC method for glycerol in water and in presence of PVP (polyvinylpyrrolidone) with UV detection??

[Uwe Neue]

For the glycerol, I suggest to use a silica HILIC column with about 75% acetonitrile and 25% water with low-UV detection. I do not know what the PVP will do. Hopefully it will be unretained.

[ym3142]

Uwe,
I just guess glycerol will have low UV even at 200nm, am I right?

[Consumer Products Guy]

We've assayed glycerol/glycerin by capillary GC after trimethylsilyl derivatization for over 25 years, from 90% levels to trace, in many matrices. So we've never even investigated HPLC for this. There's publication(s) from early 1980s such as JAOCS, Vol. 64, No. 9 (September 1987), pp. 1356-1357.

[Uwe Neue]

Low UV is a good method for sugars, so I think it will be OK for glycerol as well. It is not terribly sensitive, but it is more sensitive than refractometry. I don't know what glycerol does in a ELSD. The signal might be good enough.

[chromatographer1]

.............."Low UV is a good method for sugars, so I think it will be OK for glycerol as well............"

You are quite right, Uwe,

best wishes,

Rod

[Bryan Evans]

Sugar alcohols are well retained on our Unison UK-Amino column:

http://www.imtakt.com/TecInfo/TI308E.pdf

[juddc]

I've assayed glycerol as an ingredient in a raw material for cosmetics pretty much as Uwe suggests and it works perfectly well. Slight differences I have include a polymer based support (likely fewer theoretical plates, I think) and ~80% ACN, but it's the same idea.

Low UV detection is sufficient as long as you're not looking for trace quantities & RI works well, too. I don't know what PVP will do, but I do know that high MW hyaluronic acid doesn't pose a problem.

[Robert Brightman]

Thanks for all you help on this, as you say the biggest problem is detection and in the case of derivatization being in water limits the use of certain reagents. We are currently trying a direct gas chromatography method but haven't totally ruled out the use of HPLC. As usual the boss wants a 'simple' method for what is a difficult analysis. In the matrix there is also complexed iodine! We will check out all of your suggestions

Bob (in France)

[Consumer Products Guy]

If you are trying gas chromatography without derivatization, you may want to try the capillary detailed in USP, not too bad of peak shape, haven't tried for low glycerin levels, though, but DEG peak is sharp at low levels.

[juddc]

Complexed I2 shouldn't be a problem. You should be able to reduce it with a little thiosulfate to iodide if you need to. Years ago I worked on an interesting project where I had to determine the stability of iodine, both complexed and not, in a number of matrices and I learned a bit of Iodine chemistry on the way - really fascinating stuff, IMHO.

[Mark Tracy]

Glycerol and other 1,2 diols react with phenylboronic acid (with a basic catalyst). These derivatives can be analyzed by GC. HPLC is not good with these derivatives.