hi,

Generally RNA is not stable at -20'C. But some companies like Ambion providing buffers to store RNA at -20'C.

you have to store RNA at-80' for long term storage (1year), if u want to store for long time at at lower temp than add 3times 100% ethanol and 1/10 vol of 3M sod acetate pH (4-5) in dissolved rna and can be stored for many years.

Storage of RNA is highly appreciable in formamide for a long time. If you have that RNA dissolved in DW then it might be a prob regarding its stability till now. Dissolving in formamide and storing at -80 will help u keep it for a quite long time..

@Piyush- use of formamide is not a good choice bcoz when you want to use RNA again you have to purify RNA and so you can lost your RNA...if you have very high quantity and quality of RNA then its good...