Amino acid analysis by ion-exchange chromatography using a lithium elution gradient. Influence of methanol concentration and sample pH.

The separation of amino acids has been achieved on a short column of Chromo-Beads C2 resin, with a lithium gradient-elution system. The analysis took 8 h. The separation of asparagine and glutamine from glutamic acid was highly dependent on the sample pH and on the methanol concentration in the first buffer of the gradient. The method has been applied to analysis of human plasma and granulocytes for amino acids.