What is the recommended incubation time to stabilize tissue RNA in RNAlater?
FAQ ID -647

The RNAlater RNA Stabilization Reagent penetrates the sample by diffusion and protects RNA immediately upon contact with the surface layer and outer portions of solid tissues. In order to ensure reliable stabilization of RNA even in the inner parts of solid tissues, we recommend incubation for at least 45 minutes in the reagent prior to RNA isolation using RNeasy Kits. Note that tissue size is critical for successful RNA stabilization with RNAlater technology. Samples must be cut into slices less than 0.5 cm thick for rapid and reliable stabilization in interior tissue parts. RNA degradation will occur in tissue slices that are too thick.

For archival storage in the freezer, first incubate the sample overnight in the reagent at 2–8°C. Please see detailed instructions for storage under step 5 of the 'Protocol for RNA Stabilization with RNAlater RNA Stabilization Reagent' in the RNAlater Handbook.