Fixation of amino acids and oligopeptides by freezedrying in polyacrylamide gel electrophoresis

Following polyacrylamide gel electrophoresis in an acetic/formic acid buffer, pH 2.0, in fabric reinforced gels, amino acids and oligopeptides could successfully be fixed in the gel by freeze‐drying. Lyophilization of the fabric reinforced polyacrylamide gel after electrophoresis resulted in a dry film which absorbed ninhydrin solution quickly and uniformly, thus improving the detection limit for amino acids and oligopeptides with molecular weights ranging from 189–1045. Most amino acids were detected with a sensitivity of 0.1–0.25 μg and for oligopeptides the detection limit was found to be 0.5–5 μg.