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# Final % DMSO Concentration

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### #1 Isy

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Posted 11 April 2010 - 05:01 AM

Hi!

I am quite unsure of what does it mean by e.g. 0.5% final DMSO concentration. I had tried googling around, but am unsure if I can correct in my interpretation of the calculations.  If I had dissolved 50 ug powder into 50 uL DMSO to make a stock solution, that would give it 1% DMSO concentration. Then, if I was to use 10 ug of this stock, the final DMSO concentration would be 0.2%. Is this correct?

Thank you for any help provided.

### #2 SAnna

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Posted 11 April 2010 - 08:27 AM

Hi Isy.
FINAL DMSO concentration means the concentration of DMSO in your working solution e.g. your media, buffer ect.
When you dissolve whatever powder in DMSO you will get a stock solution made up of 100% DMSO!
[Exception: your stuff contains itself H2O, but thatīs mostly for certain salts soluble in water.]

0.5% final DMSO concentration means you give 0.5 ml of this stock solution to 99.5 ml of water (0.5 ml/100 ml*100 = 0.5%).

Now you have to combine this with the desired molarity of the stuff you dissolved: e.g. 0.5 ml of a 1 M stock of stuff X in DMSO pipetted in 99.5 ml water will give you a 5 mM working solution with again 0.5% DMSO final concentration.

Itīs important to consider the final concentration of your solvent because solvents as DMSO can have side effects depending on concentration and biological material used.

Edited by SAnna, 11 April 2010 - 08:32 AM.

### #3 Isy

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Posted 12 April 2010 - 06:27 AM

I see, I see. Thank you for the explanation.

So, if I have a stock solution of 1mM Dye X in 100% DMSO and I use 20 uL of it in 10 mL of medium (final Dye X concentration = 2 uM) , then the final DMSO concentration in the working solution is 0.2%. Is that correct?

### #4 SAnna

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Posted 12 April 2010 - 08:42 AM

Right!

If you need the corresponding formulas have a look into "Useful Dilution Techniques & Calculations" under "general lab techniques".

### #5 rhombus

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Posted 15 April 2010 - 03:48 AM

Isy, on Apr 12 2010, 03:27 PM, said:

I see, I see. Thank you for the explanation.

So, if I have a stock solution of 1mM Dye X in 100% DMSO and I use 20 uL of it in 10 mL of medium (final Dye X concentration = 2 uM) , then the final DMSO concentration in the working solution is 0.2%. Is that correct?

20ul of DMSO into 10 ml of medium is a 1:500 Dilution

A 1:500 Dilution of a 100% DMSO Solution = 0.2%

100% DMSO = 100g of DMSO in 100ml of aqueous

However 0.2% DMSO final concentration is too high for any cellular experiments. In my experience you should always be below 0.1% DMSO

Hope this is useful

Kindest regards

Uncle Rhombus

### #6 SAnna

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Posted 15 April 2010 - 08:56 AM

Thanks for adding this for clarity!
Nevertheless when you use DMSO e.g. as solvent for X-Gluc in a GUS assay with plant material, 0.2% or even higher is just fine.
It really depends on what you wanna do with it, Isy

### #7 Isy

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Posted 22 April 2010 - 05:31 AM

Thanks for showing a shorter method to calculate it.

I'm using DMSO to dissolve the dye for Calcium flux assays. The protocol in the Current Protocols in Cytometry mentioned to keep it under 0.5%.

If I would like to adjust the final DMSO concentration to 0.1%, the variable that I need to change is the DMSO volume to dissolve the dye? The final dye concentration has to be 2uM and I get that from the 1mM stock (100% DMSO).

Edited by Isy, 22 April 2010 - 05:38 AM.