All (IP-)HILIC experiments were performed on an Acquity UPLC BEH amide column (2.1 x 150 mm, 1.7 µm dp, 130 Å) (P/N: 186004802). The IPRs DEA, TEA, TPA, and TBuA, as well as AA were tested at a concentration of 15 mM in eluent A and B, where the pH of the aqueous part of the eluents was adjusted with acetic acid or ammonia to pH 7 for the IPRs and AA, respectively, resulting in the alkylamine salts (e.g., diethylamine acetate (DEAA)). Eluent A consisted of ACN-water (20:80, v/v) and eluent B of ACN-water (90:10, v/v). The gradient program started with a 1-min hold at 100% B, followed by a linear decrease of B to 30% from 1-50 min and ending with a 3 min hold at 30% B. The flow rate was 0.2 mL/min. For all ON samples, the injection volume was 1 µL unless specified differently. The poly(dT) ladder solution was injected at a volume of 5 or 10 µL. The column oven temperature was 45 °C.