a method to extract rna with high purity from biological materials containing rna in a safe , rapid , and simple procedure and a method to analyze it are provided . the procedure includes the steps of mixing a biological material containing rna with a predetermined concentration of a chaotropic agent and a predetermined concentration of an organic solvent , allowing the mixed solution to contact a nucleic acid - binding solid phase , washing the nucleic - acid binding solid - phase to which rna is bound , and eluting rna from the nucleic - acid binding solid - phase having the bound rna . furthermore , the obtained rna is analyzed by reverse transcriptase - polymerase chain reaction or the like .