Modification of approximately 65% of the amine groups of an aminopropylsilyl bonded-phase silica high-performance liquid chromatographic anion exchanger (APS-Hypersil) with organic acids containing n-alkyl moieties of different chain lengths, results in mixed mode chromatographic matrices of varying hydrophobic character. These stationary phases result in high resolution of transfer ribonucleic acids (tRNAs) when used with a decreasing gradient of ammonium sulfate. The observed resolution appears to be primarily a function of interfacial precipitation effected by the high initial salt concentration of the mobile phase and the hydrophobic character of the stationary phase, followed by selective resolubilization during the decreasing salt gradient. After resolubilization, adsorptive processes may additionally contribute to resolution. The residual amine groups decrease the hydrophobic character of the stationary phase compared to a pure reversed-phase support. The mixed-mode matrices are useful for the resolution of aminoacylated tRNAs from non-aminoacylated tRNAs.