Provided herein is method comprising: contacting an initial RNA sample containing a population of different RNA molecules with a divalent cation and a set of DNAzymes that are designed to cleave multiple target RNAs in the initial sample, thereby producing a product RNA sample that comprises: a) uncleaved RNA molecules and b) cleaved RNA fragments that contain a 2′,3′-cyclic-phosphate and a 5′ hydroxyl as the result of DNAzyme cleavage.