Separations of amino acids on silica gel, high performance silica gel, preadsorbent silica gel, microcrystalline and fibrous cellulose, and Fixion strong acid cation exchange layers were compared under standardized conditions using a mixture of the nine essential acids and a more complex 18-component mixture. Fixion layers were evaluated using three different development conditions, and loading studies of raw urine were carried out on all of the layers. Tables and figures are presented illustrating which amino acids can be resolved in each of the chromatographic systems. © 1982, Taylor & Francis Group, LLC. All rights reserved.