This is a protocol for purification of in vitro transcribed RNA via the Zymo Research RNA Clean & Concentrator™-25 kit. It works with capped and uncapped mRNA (usually >600 nt) with or without poly(A)-tails , shRNA (49 nt) and single guide sgRNA (100 nt) and yields RNA of high purity and concentration.
Christian CR Renicke (Sun,) studied this question.