How you remove DMSO depends on where it is: on your skin, in a biological sample, or dissolved in a lab solution. Each situation calls for a different approach because DMSO has unusual properties that make it stubbornly persistent. It has a high boiling point (189°C), mixes freely with water, and penetrates skin within seconds, carrying dissolved substances with it. Here’s how to handle removal in every common scenario.
Removing DMSO From Skin
If DMSO gets on your skin, wash the area immediately and thoroughly with soap and water. Speed matters here because DMSO absorbs through skin rapidly and can pull other chemicals along with it. Remove any contaminated clothing right away and launder it before wearing it again. According to UC Davis safety protocols, you should seek medical attention if irritation develops after washing.
Plain water alone is less effective than soapy water because DMSO is an organic solvent that soap helps emulsify and lift away. There’s no special solvent needed. The key is acting quickly and washing for longer than you think necessary, since DMSO that has already penetrated the outer skin layer can’t be washed off.
Removing DMSO From Cell Cultures
This is the most common lab context for the question. DMSO is routinely used at 5 to 10% concentration to cryopreserve cells, but those concentrations are toxic to living cells once they’re thawed. Research shows that 5% DMSO kills more than 30% of cells at every time point tested, and even 1% becomes cytotoxic after about 72 hours. The safe threshold for most cell types is 0.5% or less of the total medium volume.
The standard removal method is gradual dilution followed by centrifugation. You slowly add DMSO-free medium to the thawed cell suspension (gradual is important because sudden osmotic shifts damage cells), then centrifuge the mixture so the cells pellet at the bottom while the DMSO stays in the liquid above. You remove that liquid and resuspend the cells in fresh medium. Most protocols use centrifugation at around 400 g for 20 minutes at 4°C. One or two wash cycles typically bring DMSO below the 0.5% threshold.
The entire process for a single bag of cryopreserved cells takes roughly one hour. Working cold (4°C) slows cell metabolism and reduces the toxic effects of any residual DMSO during the washing steps.
Hollow Fiber Membrane Filtration
For platelet concentrates and other shear-sensitive samples that don’t tolerate centrifugation well, hollow fiber membrane filters offer an alternative. The cell suspension flows through the inside of tiny hollow fibers while a wash buffer (like phosphate-buffered saline) flows around the outside, drawing DMSO out through the fiber walls by diffusion. Optimized protocols use an internal flow rate of about 20 mL/min against an external flow rate of 100 mL/min. Even under ideal conditions, a single pass through the filter removes no more than 95% of DMSO, so a second pass or additional dilution step may be needed to reach safe levels.
Removing DMSO From Solutions and Samples
If you need to strip DMSO from a chemical solution, protein sample, or reaction mixture, the right method depends on what else is in the solution and whether it can tolerate heat.
Dialysis and Buffer Exchange
For proteins and other macromolecules, dialysis is the gentlest option. You place your sample inside a dialysis membrane with a molecular weight cutoff small enough to retain your molecule of interest, then submerge it in a large volume of buffer. DMSO (molecular weight 78) passes freely through most dialysis membranes. Multiple buffer changes over 12 to 24 hours can reduce DMSO to negligible levels. The larger the buffer-to-sample ratio, the more complete the removal.
Evaporation Under Vacuum
DMSO boils at 189°C at normal atmospheric pressure, which makes it very difficult to evaporate on a benchtop. A rotary evaporator or vacuum concentrator (SpeedVac) drops the pressure enough to bring the effective boiling point down significantly. Even so, DMSO evaporates much more slowly than common solvents like water or ethanol, and you’ll need patience. Expect longer run times and higher vacuum settings than you’d use for aqueous solutions. If your sample is heat-stable, a warm water bath (60 to 80°C) combined with strong vacuum speeds the process considerably.
Lyophilization (Freeze-Drying)
DMSO freezes at 19°C, which is above the operating temperature of most freeze-dryers. This means it can sublimate during lyophilization, but its low vapor pressure makes the process slow. Freeze-drying works best when DMSO is a minor component of an aqueous solution. For samples that are mostly DMSO, dilute with water first, then lyophilize.
Disposing of DMSO Waste
DMSO should not go down the drain. University of Washington safety guidelines classify DMSO-containing waste as chemical waste requiring proper collection and disposal through environmental health and safety services. Collect all wash buffers, rinse solutions, and other DMSO-contaminated liquids in labeled, closed containers stored in a designated area (a flammable cabinet works).
For small spills, absorb the liquid with an inert dry material like vermiculite or chemical absorbent pads, double-bag the material, and label it for chemical waste pickup. For larger spills, after absorbing the bulk of the liquid, you can spread water over the contaminated surface as a final cleaning step.
Why DMSO Is Hard to Remove
Three properties make DMSO unusually persistent. First, it’s miscible with both water and many organic solvents, so there’s no simple liquid-liquid extraction that separates it cleanly. You can’t just add water and watch it partition into a separate layer the way you would with many organic solvents. Second, its high boiling point and low vapor pressure at room temperature mean it barely evaporates on its own. At 20°C, the vapor pressure is a tiny fraction of what water produces. Third, its small molecular size (78 daltons) means it passes through most filters and membranes designed to retain larger molecules, which is useful for dialysis but frustrating if you’re trying to trap it.
These properties explain why nearly every removal strategy relies on either diluting DMSO with something else and then separating by size (centrifugation, dialysis) or applying energy to force it into the vapor phase (vacuum evaporation, lyophilization). There’s no shortcut that works across all situations, so choosing the right method starts with knowing what’s in your sample and what it can tolerate.