freezing of primers - (Jan/16/2007 )
just a quick question to everyone about how you store your primers? Do most people aliquote smaller volumes to avoid freeze thawing, and what do you use to redissolve primers...dnase free h2o or a buffer? Is it necessary to aliquote?....I have been thawing my primers each time and was wondering if I am causing them to lose some efficiency.
My primer setup is pretty much standard
I have a master stock at 100uM. This is made up with tris buffer.
And I have a working primer stock diluted to 10uM. This is diluted with sterile distilled water. My standard size is 100ul. (as I use a fair amount of primer in my colony PCR)
In the rare situation where a primer pair is in great use by the general lab, I make several aliquote of the working primer. The size is about 50ul.
If a primer is subjected to many many freeze thaw cycles, then there will be some degredation. However the main worry is contamination of the primer stock. By aliquoting your primers, you can happily dispose of your current working primer stock and take a new aliquote if ever primer contamination is suspected.
This also means that you must take very special care when making up the master primer stock.
We keep the primer stock in -20C ( it is in water). Some common primers r aliquoted to avoid freeze thaw ( also stored in -20C). For others, we make fresh primer dilutions everytime.