Licl precipitation: -80°C or -20°C; with/without ethanol; 1hour or overnightl - (Dec/13/2007 )
Usually, we use Licl to precipitate RNA. But I am puzzled about some details:
a. which temperature is better? -80°C or -20°C
b. should ethanol be used together?
c. the mixture should be stored at a low temperature for several hours or overnight?
I also applied LiCl2 to precipitate RNA.
let me give answers of your questions according to procedure in my lab. (things, that I suggest you, are working)
a-)-20 C is better
b-)your question is not clear. but still try to answer in the way that ı understood it. 70% ethanol is used after removal of LiCl2 after centrifugation.
c-)Your mix should contain 1 V of RNA, 1V of LiCl2 and 1V of ddH2O. This mix should be store at -20 C. Many procedure state that 30 min. is enough to provide RNA integration. However in our lab we applied keeping mix at -20 C for at least 1 hour 30 min. More is better, overnight incubation is even perfect.
be aware of nor loosing RNA after treatment because it will be invisible just because of cleaning of RNA