In our work, we aimed to develop a HILIC method that can resolve ONs based on their nucleobase composition and chemical modifications by reducing the influence of the phosphate backbone on retention. To accomplish this, we introduced positively charged IPRs into the mobile phase (IP-HILIC). Cationic IPRs are known to interact with the negatively charged ONs, neutralizing their charge and altering their interaction with the HILIC stationary phase. Under these conditions, the HILIC retention will be less dependent on the phosphate backbone (and thus the number of nucleotides), and resultingly, will be largely driven by the nucleobase composition and conjugated groups of the ON, unlike IP-RPLC, where the IPRs significantly increase retention due to its hydrophobicity. This process is schematically visualized in Fig. .