You might want to review the following:

As the authors articulate, there is no previous study addressing the effect of both cell density and type of solvent at the same experiment on the results of the viability assay.

http://dx.doi.org/10.1590/S1516-89132014005000007

Cell density and solvent are critical parameters affecting formazan evaluation in MTT assay

http://www.scielo.br/pdf/babt/v57n3/cd_1754.pdf

I suggest that you do not use MTT, but instead use XTT which is both soluble in aqueous media and also very well behaved.

I typically remove media from my cells, wash, and then incubate with XTT/PMS for 15-25 minutes, reading the absorbance in the plate reader to make sure I am in the linear portion of the product formation curve.

Then I remove the XTT, rewash, and assay the same wells for Lactate dehydrogenase levels using Lactate/NAD/Diaphorase and Resazurin.

This way I have a measure of anaerobic/aerobic respiration in each well. The levels of LDH and mitochondria in all the mammalian cells I have examined are not invariant.

Try ethanol or Acetone. These solvents should not show absorbance because you are taking lectures in a range of 540 and 570 nm

Hi Bhavapriya

A mixture of DMSO and ethanol 1:1 works quite fine in my experiments.

Good luck!

Hi,

We are using DMSO:MeOH=1:1 to dissolve the formazan dye.

No.

Hi, Bhavapriya: you can use DMSO directly. it will not affect your data. 

Better solution: Please use MTS. a water soluble tetrazolium. No headache for desolving its crystal.

Goog luck!