Hello,
I have used a 14kDa dialysis bag made from cellulose. I put some food dye in there. (10mL food dyed water and 200mL external buffer).
It has taken about 3 days for equilibrium to be reached.
I need equilibrium to be instantaneous (ideally) or within 1 hour.
Does anyone have any ideas why it is taking 3 days, and how I can reduce this? Not sure if I need to increase the membrane cut-off? Also, I have done at room temp, would body temp reduce it from 3 days to 1 hour?!
Thank you.
Dear Lara
Just a question: Are you using the food dye just as a tool to follow the dialysis progresses?
3 days are a long time. Did you stirred the buffer outiside the membrane?
I think that under stirring in 6-8h with a membrane with 14Kda cut-off you can reach the equilibrium. Of course a membrane with large pore will reach the equilibrium faster but however the size of the pore depends from the size of the molecules that you would like to retain inside you membrane.
An alternative to dialysis to perform rapid buffer exchange in few minutes for small volume samples, at least for samples with MW>2KDa is the desalting.
if you are interested to know more details about it, you can find more informazion on my blog: ProteoCool ( https://proteocool.blogspot.com/ )
good luck
Manuele
Hi,
In order to decrease the time of the dialysis process, I recommend you to focus on the external buffer volume, composition (ionic strength) but also its exchange frequency and time intervals...The external buffer should be at low ionic strength as possible as you can adjust. Besides, you need to exchange and use a fresh external buffer in a short certain time period for several times as Manuele Martinelli suggests. If applicable you may also use larger volume external dialysis buffer for complete equilibration in a short time. (e.g. 2 L or greater volumes instead of 200 ml).
These are the common troubleshooting that I can recommend, apart from the consideration of increasing the membrane pore size.
Good luck,
Emir...
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