Hello,
As you read the title, I prepared 344.44 mM edaravone in DMSO in the room temperature.
Would you tell me whether the edaravone powder is completely dissolved?
I can show you a picture on the edaravone solution.
I put the 3 g of edaravone powder in a 50 mL volumetric flask, and then I poured 99.9% DMSO up to 50 mL line, and the molarity is 344.44 mM
However, I have known that the maximum solubility of edaravone in DMSO is 100 mM (https://www.tocris.com/products/edaravone_0786).
Please let me know why it happened as soon as possible.
I need your help, and thank you for reading and answering my difficulty.
Thanks a lot!
Hi Seulki,
If your compound doesn't dissolve, you should be able to see a precipitate when you centrifuge your mixture. So, take an aliquot, add it to an eppendorf, and centrifuge it.
If there is no precipitate, there's also a possibility that your compound forms colloids. To check if it is a colloid, you can use light scattering (also called Tyndall Effect - google it - it's pretty). So, shine a laser pointer through your mixture, and see if you can see the light path.
Dear Kelvin Anggara,
Hello, Thanks for your answer, and I have one more question.
Is the 344.44 mM Edaravone solution a colloidal solution?
The reason why I asked the question is that I wonder if colloids can look like bubbles.
Hello, I took 2 mL of the aliquots of distilled water, 100 mM Edaravone solution, and 344.44 mM Edaravone solution, and then I tried to see the light direction. The centrifuge condition was 2 minutes at 17,000 RPM (19,386 g). Also, I shined the light to the distilled water, 100 mM of Edaravone, and 344.44 mN of Edaravone, which are not centrifuged.
After finishing the centrifuge, I could not see any precipitation; thus, I turned the light and observed whether the light was scattered or not. I could notice that the light path in the 344.44 mM of Edaravone solution was straight, and I once concluded that 344.44 mM of Edaravone in DMSO is a colloidal solution. I attached the picture of the result of the Tyndall Effect.
I guess that powdered Edaravone solvents should be made up to 100 mM.
Dear Seulki Choi,
It's hard to figure out from the pictures you uploaded. It may be a colloid (not obvious), or possibly there's an error in the supplier's data sheet, or just maybe you have a different more soluble crystal form.
One thing that may help is to run a series of UV-Vis spectra, on your concentrated solution as well as on, for example, 1:1, 1:2 and 1:3 dilutions with DMSO. Then focus on the wavelength of one of the maxima (e.g. for the phenyl group around 260 nm). If this is a true solution, the Beer-Lambert's law should be followed there, so the absorbance should be proportional to the concentration. In addition, if you see a flat featureless non-zero background absorbance anywhere in the 200-800 nm range it's likely to be due to scattering by a colloid. Presence of some colloid does not rule out the possibility that most of the material is dissolved.
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