Method and system for RNA analysis by matched ion polynucleotide chromatography

Abstract

A Matched Ion Polynucleotide Chromatography method and system for size-based segregation of a mixture of RNA molecules. The method includes applying the mixture to a reverse phase column containing polymeric beads and eluting, preferably under denaturing conditions, the RNA molecules with a mobile phase which includes counterion reagent and an organic component. The method can be used in segregating RNA molecules having lengths in the range of about 100 to 20,000 nucleotides. Improved segregation is obtained using a chromatography column having an ID greater than about 5 mm.

The invention claimed is:  
     
         1 . A chromatographic method for segregating a mixture of RNA molecules having lengths exceeding about 100 nucleotides, said method comprising: 
 a) applying a solution of said fragments and counterion reagent to a column containing polymeric beads having non-polar surfaces, wherein said beads have an average diameter of about 1 to about 100 microns;    b) eluting said RNA molecules with a mobile phase which includes said counterion reagent and an organic component.    
     
     
         2 . A method of  claim 1  wherein said eluting is carried out under conditions effective to denature the secondary structure of said RNA molecules.  
     
     
         3 . A method of  claim 1  including collecting mobile phase fractions containing said RNA molecules.  
     
     
         4 . A method of  claim 1 , wherein said mobile phase comprises a counterion agent and an organic solvent, wherein said organic solvent is water soluble.  
     
     
         5 . A method of  claim 4 , wherein said solvent is selected from the group consisting of alcohol, nitrile, dimethylformamide, tetrahydrofuran, ester, ether, and mixtures of one or more thereof.  
     
     
         6 . A method of  claim 4 , wherein said solvent comprises acetonitrile.  
     
     
         7 . A method of  claim 1  wherein said counterion agent is selected from the group consisting of lower alkyl primary amine, lower alkyl secondary amine, lower alkyl tertiary amine, lower trialkyammonium salt, quaternary ammonium salt, and mixtures of one or more thereof.  
     
     
         8 . A method of  claim 7  wherein said counterion agent is selected from the group consisting of octylammonium acetate, octadimethylammonium acetate, decylammonium acetate, octadecylammonium acetate, pyridiniumammonium acetate, cyclohexylammonium acetate, diethylammonium acetate, propylethylammonium acetate, propyldiethylammonium acetate, butylethylammonium acetate, methylhexylammonium acetate, tetramethylammonium acetate, tetraethylammonium acetate, tetrapropylammonium acetate, tetrabutylammonium acetate, dimethydiethylammonium acetate, triethylammonium acetate, tripropylammonium acetate, tributylammonium acetate, tetrapropylammonium acetate, tetrabutylammonium acetate, triethylammonium hexafluoroisopropyl alcohol, and mixtures of one or more thereof.  
     
     
         9 . A method of  claim 2  wherein said eluting is carried out at a temperature greater than about 60° C.  
     
     
         10 . A method of  claim 9  wherein said eluting is carried out at a temperature within the range of about 40° C. to about 80° C.  
     
     
         11 . A method of  claim 1  wherein the pH of said mobile phase is within the range of about pH 5 to about pH 9.  
     
     
         12 . A method of  claim 11  wherein the pH of said mobile phase is about pH 7.  
     
     
         13 . A method of  claim 1  wherein said mixture comprises RNA molecules exceeding about 1,000 nucleotides.  
     
     
         14 . A method of  claim 1  wherein said mixture comprises RNA molecules having up to about 20,000 nucleotides.  
     
     
         15 . An improved method for segregating a mixture of RNA molecules by Matched Ion Polynucleotide Chromatography, said mixture comprising molecules having lengths exceeding about 100 nucleotides, the method comprising: 
 a) applying a solution of said molecules and counterion reagent to a column containing polymeric separation beads having non-polar surfaces, wherein said separation beads have an average diameter of 1 to 100 microns, said column having an ID greater than about 5 mm;    b) eluting said RNA molecules with a mobile phase which includes said counterion reagent and an organic component.    
     
     
         16 . A method of  claim 15  wherein said eluting is carried out under conditions effective to minimize the secondary structure of said RNA molecules.  
     
     
         17 . A method of  claim 15  wherein said eluting is carried out at a temperature within the range of about 40° C. to about 80° C.  
     
     
         18 . A method of  claim 15  wherein said ID is greater than about 7 mm.  
     
     
         19 . A method of  claim 15  wherein said ID is greater than about 10 mm.  
     
     
         20 . A method of  claim 15  wherein said ID is greater than about 50 mm.  
     
     
         21 . A method of  claim 15  wherein said ID is in the range of about 5 mm to about 1 m.  
     
     
         22 . An improved reverse phase chromatography column for segregating a mixture of RNA molecules by Matched Ion Polynucleotide Chromatography, the mixture comprising molecules having lengths exceeding about 100 nucleotides, the column comprising: 
 a cylinder containing polymer beads, said beads having an average diameter of 1 to 100 microns, said beads being unsubstituted polymer beads or polymer beads substituted with a hydrocarbon moiety having from 1 to 1,000,000 carbons, said column having an ID greater than about 5 mm.    
     
     
         23 . A column of  claim 22  wherein said ID is greater than about 7 mm.  
     
     
         24 . A system for segregating a mixture or RNA molecules by Matched ion Polynucleotide Chromatography, comprising: 
 the column of claim  22 .