Chromatography Forum

I am trying to develop a method for the determination of dimethylselenoxide and dimethylselenone. They are selenium analogs of DMSO and dimethylsulfone (MSM-methyl sulfonyl methane). There aren't many references for these selenium species and the references for DMSO and DMSO2 use GC (i only have HPLC). Anybody have experience with separation of DMSO and MSM using HPLC that I may apply to these selenium analogs?
Thanks

This sounds like quite a challenge to get it running on HPLC, while it's straightforward with GC. Here are some topics that might be helpful:

https://chromforum.org/viewtopic.php?t=14301

https://www.chromforum.org/viewtopic.php?t=1064

What is the sample matrix, and which detector(s) do you have on the HPLC?

Hi, thanks for responding!
I have my HPLC coupled to an ICPMS so I monitor S and Se and this provides ng/L sensitivity for Se (an order of magnitude higher for S). Probably the best detector for heteroatom containing organic molecules. Coupling the GC to an ICPMS is harder. Also since all my samples are waters, I am thinking it will even be harder with GC since I would have to somehow get it in a GC compatible solvent first???.

One of my biggest challenges is the degradation of DMSeO and DMSeO2 to dimethylselenide during separation. I can not get these two separate. They come out in the dead volume like DMSO and DMSO2 come out in the dead volume with the 3 C18 columns and 2 SCX columns I tried. I usually see the bridging two peaks of DMSe and DMSeO when I inject the DMSeO.

Thanks...

Should be similar to this:
https://helixchrom.com/compounds/dimethylacetamide/

With GC, you'd be ideally be using headspace for DMSO in water. The separation between your 2 analytes would be easier i think.

I'm sorry i can't recommend an LC column to separate these 2. Monitoring selenium by ICPMS sounds good. I don't get why DMSeO and DMSeO2 would reduce to DMSe? How did you conclude this, if I understand correctly none of the species are separated?

It is mostly DMSeO that degrades to DMSe. The disclaimer here is that I have synthesized the DMSeO std. When I try different columns and and different mobile phases, I get varying ratios of DMSe and DMSeO in the chromatograms (consistently) so I am thinking somehow this degredation is happening on column with the eluant. DMSe elutes 4-8 minutes later depending on eluant. DMSeO injections show up like a bridge where the first peak is DMSeO with a huge tail and the second peak is DMSe with a huge fronting. Hard to explain without a chromatogram...

Thanks

Should be similar to this:
https://helixchrom.com/compounds/dimethylacetamide/

This does sound interesting. Thank you very much. Do you think DMSe and DMDSe will elute at a reasonable time in these conditions?

With low organic (0-5%) you should have enough retention. If you can send me samples (5-10 mg each), I can run this in the lab and share data with you.