An old and stupid questions for all the newer of cell culture..
I found that there are two definitions of split ratio on the web:
1. 1:7 = 1ml of cell resuspended + 9ml of medium
2. 1:7 = 1ml from 7ml cell resuspended + 10ml of medium
Currently I'm doing the second one but I wonder if I have the right concept about split ratio
Yes, split ratio 1:7 means that you should pass on 1/7 of the cells from a flask to a new flask! When it comes to volumes, you should use enough media to inactivate the trypsin, and the media level should be constant in the same size of flasks to ensure the same level of gas exchange. Therefore you should choose whether you want to use e.g. 10, 11 or 12 ml media in the 75 cm2 flasks, and keep it constant.
If you are to split the cells 1:7 I would take 1/7 of the cell suspension and pass it on to a new equal sized cell flask together with as much new media that is suitable for the size of the flask. Also, the volum you resuspend your cells in depends on the size of the flask and how much e.g. trypsin you use to deattach the cells with. If you use a 75 cm2 flask I would reccomend 12 ml media in total, 1 ml trypsin for deattaching cells, and then 9 ml fresh media with serum to resuspend the cells in. So in my case I would have 10 ml in total, and then pass on 10/7 = 1,4 ml cell suspension to a bottle of the same size and add fresh media up to 12 ml...or 10 ml if you'd like to use that volume.
Thanks Coaroline for your answer. Just rephrase your answer if I get it correct.
Split ratio does not depend on how much new media added to a new flask (if we are splitting the cell from same sized cell flask).
Split ratio depends on the volume of trypsin + medium to deactivate trypsin + cell.
Yes, split ratio 1:7 means that you should pass on 1/7 of the cells from a flask to a new flask! When it comes to volumes, you should use enough media to inactivate the trypsin, and the media level should be constant in the same size of flasks to ensure the same level of gas exchange. Therefore you should choose whether you want to use e.g. 10, 11 or 12 ml media in the 75 cm2 flasks, and keep it constant.
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