Aspects of the disclosure relate to liquid chromatography (e.g., HPLC) methods which enable high resolution separations of polynucleotides of various lengths, sequences, and/or base compositions in a highly tunable manner. In some embodiments, the disclosure describes liquid chromatographic methods for separating a nucleic acid (e.g., a polyadenylated nucleic acid, such as an mRNA) from a complex mixture by using multiple ion pairing agents in the same mobile phase system. Accordingly, in some embodiments methods described by the disclosure are useful for assessing the quality of pharmaceutical preparations comprising nucleic acids.
