Hi all,

I am synthesizing a sulfinic. One byproduct is the corresponding sulfonic acid.

Has anyone some experience with the separation of sulfinic and sulfonic acids by HPLC ? I am thinking of doing ion pairing with tetrabutylammonium something, but my first trials with TBAHS showed no separation. Any idea is welcome !!

Gil.

I have never attempted the separation of a sulfinic from a sulfonic acid.

However, I would try to leverage the difference in their pKa's. An alkylsulfonic acid will be a strong acid with a pKa something like -6 (methanesulfonic acid)while the same alkylsulfinic acid will have a pKa of about 2 (methanesulfinic acid).

I would try to achieve a seperation by picking a mobile phase at a low pH (~2) and attempt to protonate (partially)the sulfinic acid and increase its reverse phase retention. Possibilities are TFA and phosphate. Do not use an end capped column. I would probably use one of the "stable bond" C18 columns (diisopropyl protecting proups) because they offer some protection against the acid hydrolysis of the siloxane bond.

Good Luck

adding to Tom M response........I have gotten good retention of some sulfonic acids in 100% water and 1:1 phosphoric acid:dihydrogen phosphate buffer. For example, the mono subsituted sulfonic acid of isophthalic acid is reasonably retained on Sperisorb ODS 2 or any of the "aqueous" columns-Aquasep, Aquasil, ODS-AQ. (for reasons I never understood, the para isomer of sulfonated phenol requires ion pairing) Do not use Prism as it has basic sites and anions can tail on it. Aquasep from ES Industries is the most retentive for sulfonic acids I have tried) One would presume if you can get reasonable retention of the sulfonic acid, the sulfinic would be more retained.

No doubt there will be hydrolysis of the stationaly phase under these conditions, however, I used a Spherisorb ODS 2 off and on under these conditions for several years with no significant change in retention.

If that fails, try tetramethyl ammonium ion pairing, or ion exchange.

here is another thought that worked for a related problem. Lower the pH to near 2 with phosphoric acid and add tetrabutylammonium something, I like phosphate. If there was no separation with both ion paired, then this approach may protonate the sulfinic acid and reduce or eliminate ion pairing with TBAXX. Sulfonic acid will remain unprotonated and will pair, presumably. this worked for the separation of two carboxyllic acids of quite different pKa.

Hi all!
We are running HPLC in cesium formate solution to separate and detect sulfate. The solution might contain oxalate and some 2-acryl-amido 2 methyl propane sulphonic acid. Can one of those cause interference of the sulfate determination? Prior to diluting the sample 100 times, the weight % CsFormate (CsHCOO) is +/- 75%.
Thanks for any help to this!

Dear all,
I am first time user of this website and urgently need your help to resolve my problem. I want to quantify the betaine (glycine beteine) from plant samples using pure betaine as control. The same work has been done using the Sperisorb ODS2 and Sperisorb 10 SCX cloumn.
In our lab we have a Haisil 100 C18 5uM column. Can I use the Hasisl 100 C18 column for betaine (pKa 1.84; Carboxylic acid)quantification?
Is Sperisorb ODS2(C18) is equal to Haisil 100 C18? as both work in range of ph 2-8 with pore size 5 uM.