I am preparing drug stock in DMSO. To take the weight of drug I need to expose it outside the cabinet. Thus I am wondering about microbial contamination. Do I need to filter it with 0.22um syringe filter?
I agree with the comments that 100% DMSO is too toxic for microorganisms (never mind the toxicity of the concentrated stock of drug/compound you just dissolved!).
We tend to use 'hybri-max' tissue culture grade DMSO for our experiments, FYI. Anyway, you cannot filter DMSO through a syringe filter unless you have purchased DMSO resistant filters, so be careful.
Of course, you need to filter your samples before assay. When you take out your sample outside of the cabinet, it must be contaminate. Microbes are so sensitive. When you filter, you use 0.2 um syringe filter. Anyway, you will use autoclave DMSO also.
Requirement for filtering your drug preparation depends on the concentration of the final drug preparation and also the amount of drug you will have to add to your system. If it is a low quantity that you add to your system, you dont have to filter it. Filtering the solution will not affect the result. But, you dont have to necessarily filter it for fear of contamination. DMSO is also quite toxic to cells and does not support the growth of most 'animalcules'.
Dear Bhuiyan, I am using autoclaved DMSO. But while filtering it get stucked in the 0.22um filter may be for it's chemical nature. As DMSO at its concentrated form usually not support microbial growth, I just thinking to skip filtering steps. Anyway, thanks for your suggestion. May be I should measure inside the cabinet.
Dear Janaka, I agree with your comments on DMSO toxicity. May be measuring the drug amount inside cabinet will solve the microbial contamination problem, right now I am thinking. For that I need to measure in less sensitive balance and higher amount of drug. Thanks for your suggestion.
Dear Mr. Hafiz, you can dilute your DMSO with deionized water. You can use 0.5 to 1% DMSO solution.
I agree with the comments that 100% DMSO is too toxic for microorganisms (never mind the toxicity of the concentrated stock of drug/compound you just dissolved!).
We tend to use 'hybri-max' tissue culture grade DMSO for our experiments, FYI. Anyway, you cannot filter DMSO through a syringe filter unless you have purchased DMSO resistant filters, so be careful.
I alwasys use cell culture grade DMSO and autoclaved tubes to prepare drug stocks (1000×) inside the cabinet. it is a very low quantity that I add to the system, no microbial contamination, I didn't filter the stock and I measured the drug amount outside the cabinet too. In fact many drug/compound we used are very expensive and we got very low volum stock, it is not convenient to filter them.
Thanks Fen Li... I also feel the inconvenience of filtering and loss of drug. Your experience will be a help for me.
DMSO will dissolve many filters. Don't go there.
It's actually surprisingly non-toxic stuff - which poses its own problems - unlike other solvents, spores can survive in 100% pure DMSO.
In response to Robert, I admit haven't done any real research into the toxicity of DMSO on fungal spores, but certain (human cancer) cells that I have used are quite sensitive to DMSO in excess of 1% so 'surprisingly non-toxic' is a relative description.... Either way, I reckon you'd be pretty unlucky (or you have a heavily contaminated lab) to encounter a genus of fungi in your TC which can survive in 100% DMSO.
Use Cell culture grade DMSO, it will solve your issues. Weighing drugs- do not worry about contamination there, worry about moisture because it degrades the compound. Read about microbes present in air ; negative pressures rooms are built for such purposes.
Make a stock, which is highly concentrated, 1000x oder even 10.000x if this is possible and make a working dilution from that to go into the cell culture. Then you minimize the amount of DMSO in your medium.
Filtering or autoclaving of 100% DMSO is not necessary, since nothing will grow in there. DMSO is as well a good solvent for a lot of plastics, so be careful with filtering.
If it is possible you can search for an alternative solvent for the desired drug; then you can strile it through syringe filters.
Filtering is not necessary if you dissolve your drug in 100 percent MDSO.
Nylon and PTFE filter are resistant to DMSO. Nylon filter should be not too expensive. If you want to try.
In terms of filtering DMSO and many other compounds check these references...makes life that much easier to chose the right filter if needed:
http://www.restek.com/pdfs/GNTS2122-UNV.pdf
https://www.corning.com/media/worldwide/cls/documents/CLS-FIL-004%20REV4%20DL.pdf
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