Can miRNA and other RNAs smaller than 200 nucleotides be isolated with the AllPrep DNA/RNA Micro Kit or RNeasy Plus Micro Kit?
FAQ ID -1749

Yes, RNAs smaller than 200 nucleotides, including miRNA, can be isolated using the AllPrep DNA/RNA Micro or RNeasy Plus Micro Kit. Please follow the specialized protocol 'Purification of total RNA containing small RNAs from cells' in Appendix D of the AllPrep DNA/RNA Micro or the RNeasy Plus Micro Handbook, respectively.

Please note that this protocol is for use with cultured cells only, and is not compatible with tissues.