Abstract A nitrongen-specific gas-chromatographic detector has been used to analyse amino acids in the low picomole range as their N-heptafluorobutyryl isobutyl esters. The amino acid derivatives were studied over the range 3–60 pmol and a coefficient of variation of <4% was obtained for the relative molar reponses of most of the monobasic amino acids. A detection limit of ca. 250 fmol was established for the monobasic amino acids. No simple relation could be established between detector response and the atomic composition of the amino acids. The specificity of the detector allowed the nitrogenous components of complex physiological samples to be analyses without prior fractionation of the samples.