JLC-5AH

The JEOL JLC-5AH is an amino acid analyzer. The JLC-5AH was the first amino acid analyzer in the world. JEOL introduced the JLC-5AH in 1968.^[1]

An amino acid analyzer typically operates by ion-exchange chromatography. The sample is injected onto a column packed with a cation-exchange resin. Amino acids are eluted by a gradient of buffers with increasing pH and ionic strength. The eluate is mixed with ninhydrin reagent and heated, producing a purple color (Ruhemann's purple) that is measured spectrophotometrically. The absorbance is proportional to the amino acid concentration. The instrument generates a chromatogram with peak areas corresponding to each amino acid.

The JLC-5AH fits into the analytical workflow following sample preparation. For protein analysis, the protein is first hydrolyzed into its constituent amino acids. The hydrolysate is then loaded onto the analyzer. The instrument resolves the mixture and reports the amino acid composition. For physiological fluids, samples may be deproteinized before injection. The output is used for protein characterization, nutritional analysis, or clinical diagnostics.

The JLC-5AH was used in the analysis of aculeacin A, an antifungal antibiotic. After acid hydrolysis of aculeacin A, the JLC-5AH detected five ninhydrin-positive fragments, including threonine and hydroxyproline. The JLC-5AH was also employed in a study of human C-peptide kinetics to determine the concentration of synthetic human C-peptide solutions by amino acid analysis.^[2][3]