MSM

[Fernando]

Does anyone know a RP method for MSM (Methyl Sulfonyl Methane) with UV detection? Thanks for any help

[Cliff Mitchell]

Is that dimethyl sulfone? I have tried to do UV-LC on this and didn't see any absorbance at all. Maybe if you try 190nm.

[Fernando]

Hi Cliff

Yes I tried 195 nm and there is not much absorbance at all, to your question MSM is (CH3)2 SO2.
While I was waiting for the drug I tried with DMSO (DiMethyl Sulfoxide) wich is very similar and I have no problems at all with RP-LC with UV detection, I worked with an RP-18 column an acetonitrile-water mobile phase.
But with MSM NOTHING!!!

Thanks for your reply

[Cliff Mitchell]

Now that I think about it, DMSO has a lone pair on the sulfur and dimethylsulfone does not, so there will be no electronic transitions. You will probably have to go to another detector, RI or ELSD.

[Fernando]

Hi Cliff

Yes you are right, but in our Lab we don´t have any other detector than UV (DAD).

Thanks all the same!

[Cliff Mitchell]

I don't know how viable this idea is, but perhaps you could use inverse detection, find/make a highly absorbing mobile phase and detect negative peaks. Ideas from others?

[Kostas Petritis]

Indirect UV detection could work, although it might be difficult to set up the appropriate method and you might have relevant problems discussed in previous posts (i.e. system peaks etc...).

[Fernando]

Hello Cliff, Kostas

The peaks I obtained with MSM are awful, and I was injecting the standard
all I am sure is that I did not have the right column or the right mobile phase.
In the sample there is the MSM and two UV absorbing drugs in the tablet making the separation almost imposible.

Thanks for your ideas.