Selective precipitation of large RNAs.

For reasons that are somewhat mysterious, "large" RNAs ≥100 nucleotides long can be selectively separated from small RNAs <100 nucleotides long by precipitation with either LiCl or PEG/NaCl. These methods are very straightforward, and are valuable for enriching for very small RNAs (i.e., miRNAs) in unprecipitated material while retaining all other RNAs in the precipitate.