ABSTRACT
Automated amino acid analysis was first introduced by Moore and Stein 1 in the 1950s. Together with Spackman 2 they developed an amino acid analyzer that automatically coupled the amino acid separation with quantitation based on the ninhydrin reaction. Essentially amino acids are separated by cation exchange on cross-linked sulfonated polystyrene using citrate buffers. The use of a “microbead” resin with a uniform diameter of about 10 μm or less improved buffer composition, and high pressure chromatographic techniques have decreased the analysis time from 24 hr to approximately 1 hr, while microbore columns and improved spectrophotometer design have increased sensitivity about 100-fold. The increased sensitivity of amino acid determination has, however, also depended greatly on the introduction of new postcolumn fluorogenic detection reagents.
