Using the standard protocol, RNAs ≥ 25 nt can be purified. With a slight modification in the protocol (adding 2 volumes of ethanol instead of 1 volume after addition of the binding buffer), RNA > 15 nt can be purified.

Please note that recovery of small RNAs (< 45 nt) can be affected by sequence, interactions with other nucleic acids and/or secondary structure.

*Secondary structure was predicted using RNAstructure Web Server: Reuter, J. S., & Mathews, D. H. (2010). RNAstructure: software for RNA secondary structure prediction and analysis. BMC Bioinformatics. 11,129
If poor yield of a small RNA is observed using the standard RNA Cleanup Protocol (adding 1 volume of ethanol prior to binding to the column), we recommend using the modified protocol (adding 2 volumes of ethanol prior to binding to the column), which uses a higher ethanol-to-sample ratio to shift the exclusion cut-off and enable the capture of smaller RNAs.