I wrote the first paper mentioned in the above comment. Thank you for your interest in my work. You will need to slightly modify the elution gradient. Also make sure to use a very high source temperature since DMSO has a high boiling point.

This has been getting a bit of airtime on LinkedIn and ABRF. The consensus seems to be that it is instrument dependent. Some instruments it does as the paper says, some report no difference. No one has reported any deleterious effects and some have suggested that it will improve the longevity of pumps seals in the chromatograph. If it has no effect on ionisation, one reason for doing it is a reported drop in sample carryover from cycle to cycle. I haven't had a chance to try it on our QSTAR Elite/Tempo system. When things quiet down after honours students finish, I'll make time to try it.

Another thread on this can be found on SharedProteomics (www.sharedproteomics.com). I would suggest to pick up the existing threads as Matt suggests.

DMSO is usually used as solvent for hardly soluble substances in any other solvent. the only reason using DMSO as an additive is the probability of enhancing LC separation only. However, the effect on ion suppression to ESI-MS, could be easily decided by applying same conditions without using DMSO, observing the MS response. I expect, little ionization suppression, since I could found no reports on this. But, a compound like Dansyl ions is known to greatly affect the ESI-MS (ionization suppression). DMSO contain same functional group SO2, but it is not ionized like Dansyl, it is just gives little polarity to the solvent. Your question needs Practical testing, it is very nice-smart, question.

DMSO should be beneficial to keep into solution some hardly soluble substances without having any drawback regarding cleanliness of source. I think that can be used both with the ESI source and APCI source.

Dear Dr Steger; I did simple experiment to find out the difference. I prepared right now, two solutions and infused to ; ESI-ION TRAP MS AGILENT 6320 and the TIC-MS1 was recorded (rate 10 uL/h); SOLUTION A = [5 mL acetonitrile + 0.2 mL 0.1M Na acetate (+ 5 mL g acetic in 50 mL 0.1M sod acetate)]

SOLUTION B = [4 mL acetonitrile + 1 mL DMSO + 0.2 mL 0.1M Na acetate (+ 5 mL g acetic in 50 mL 0.1M sod acetate)]

Results: DMSO showed little suppress the ionization to form cluster ions.

Have a look to the attached IT-MS figures.

DMSO affects Peek connections and seals in higher concentrations. Another fact - background peaks and ionization suppression can not be inhibited. From my experience -do not DMSO directly in the MS system (eluent).

But it is entirely possible:

Prepare a stock solution of your sample in DMSO and then dilute with ACN, MeOH or ACN-DCM (low ammount DMSO).

You may want to look at two recent papers from Komives and Kuster labs that recently came out in JASMS and Nature Methods recently. Both papers report improvements in peptide/protein identification rates upon addition of DMSO to LC solvents. Kuster lab reports up to 10 fold improvement in sensitivity by adding DMSO to the LC solvents. I have pasted the links below.

http://link.springer.com/article/10.1007%2Fs13361-012-0404-0

http://www.nature.com/nmeth/journal/v10/n10/abs/nmeth.2610.html

I wrote the first paper mentioned in the above comment. Thank you for your interest in my work. You will need to slightly modify the elution gradient. Also make sure to use a very high source temperature since DMSO has a high boiling point.

Addition of DMSO has some advantages specially related to substances with poor solubility , however it may cause ion supression

I recommend you to directly contact Bernhard Küster from the Technical University Munich. The Küster group should have "long-term experience". I guess it was this paper you are reffering to:

http://www.nature.com/nmeth/journal/v10/n10/abs/nmeth.2610.html

However, as already mentioned, DMSO can lead to swelling of PEEK. If you have steel capillaries or PEEK-sil, it should not be a problem. If you are using a Trapping column, you should use no DMSO in the "Trapping solvent". Otherwise, peptides will be washed into the waste by the 5% DMSO. I don't whether your system has separate pumps for Trapping flow (without DMSO) and analytical flow (+5% DMSO). A setup without a trapping column can be directly used with the addition of DMSO.

We only use sil or PEEKsil. Yes we have separate pumps and besides the MS improvement I already contemplated about adding 5% DMSO to buffer B of the trapping pump to reduce sample carryover. So far we use trifluoroethanol (5%, but only as blank injection solution, not in the buffer), but maybe DMSO outperformes TFE.

Thanks for all the comments, I think it is worth trying this approach.

@Mirco ,

A month ago you mention that you are going to try DMSO in your gradients..

I am interested to hear about your experiences.. did it work?

More signal? less background? less carry-over?

@Antoine

Sorry, I haven´t got the opportunity to test the effect yet. To many things to do at the moment....

This method recently was cited by Dr. Josh Coon at U.W. Madison to observe the one-hour yeast proteome. .

http://www.nature.com/nmeth/journal/v10/n10/full/nmeth.2610.html

Sorry, I meant to post this link:

http://www.mcponline.org/content/early/2013/10/19/mcp.M113.034769.long

Thanks for the link, quite impressive data!

Hi Mirco,

One of the major drawbacks will be the slow erosion of HPLC components... for instance seals and other non-metallic components of your LC, and the LC column itself. Also, DMSO is a very powerful solvent, so you may only want to use with very hyrdophobic compounds to effect elution. Anything that elutes relatively soon in a standard chromatgram will be swept off the column easily with DMSO added (perhaps in the void volume peak). DMSO is great as a cleaning injection... i.e, if you have a contaminate on your HPLC that you want to pull off the column... a small injection of 100% DMSO (a 'slug' of DMSO) will most likely remove these impurities.

Thanks for your answer. As a first step I will test DMSO only as an additive for a cleaning injection to get rid of contaminations.

Does anyone know if DMSO (abovementioned papers) only improves the ionization of peptides or does it also work for other compounds and in negative mode?