The ligand in CIM C4 HLD monoliths is a hydrophobic butyl group. RNA binds on the column under hydrophobic conditions. The majority of DNA and short transcripts elute earlier than intact ssRNA, while most of the proteins and aggregates bind very strongly and are eliminated by a cleaning step with NaOH. C4 HLD can be used to produce research grade ssRNA from in vitro transcription (IVT) mixtures but gives its best results as a polishing method.
The sample is applied at elevated concentrations of salts that precipitate RNA. The high salt concentration enables binding on the column. A decreasing salt gradient, or a step elution can be used to elute RNA from the column. Fractionation of the elution peak is recommended to analyze for purity (fragments).