Hello,

An effective and simple way to do so is that you can use thick aluminium foil. Wrap your samples with aluminium foil and snap chill in liquid nitrogen and then place those in a container of dry ice. you samples will be perfectly good to go for the RNA isolation while carrying over more than 20 hrs.

Hope this will help you.

Thank you Arnab Majumdar . This will help a lot.

Is it an overfilling problem?

Paul Milham . No sir.. The samples are 1/4th the capacity of the tubes.