A LITHIUM BUFFER SYSTEM FOR SINGLE-COLUMN AMINO ACID ANALYSIS

The separation of threonine, serine, glutamine, and asparagine without losing the resolution of most other common ninhydrin-positive substances was achieved using a Technicon single-column amino acid analyzer; the resolution in other areas of the chromatogram was also improved. The modifications to the standard procedure were restricted to substituting lithium citrate buffers for sodium citrate buffers and converting the Technicon type A resin from the Na+ form to the Li+ form. Only two buffers were required. The column temperature was changed from 33° to 55° 5 hr after the start of the analysis and the total analysis time was 21 hr. The technique was applied with success to the analysis of the acid-soluble ninhydrin-positive substances in human blood plasma, and should be applicable to the analysis of a variety of plant and animal tissues. © 1969 Academic Press, Inc.