Simultaneous quantitation of twenty-two amino acids in nanolitre samples of biological fluid

The technique of thin-layer chromatography and 14C-dansylation has been used for simultaneous measurements of 22 individual amino acids, taurine, serotonin, and gamma-aminobutyric acid in nanolitre samples of glomerular and renal tubule fluid. Standard curves of each amino acid mixture containing all the others showed excellent linearity at amounts ranging from 5.7.10(-13) to 1.45.10(-11) mole (regression coefficients all greater than 0.95). With careful standardization of dansylation conditions, the technique permits highly reproducible measurement of less than 1 pmole of an amino acid.