Ultramicrodetection of Amino Acids by GLC

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Abstract
A method has been developed for the separation and qualitative detection of 11 amino acids at the picogram level, which uses a derivatization new to the area of gas-chromatographic analysis. Phosphorus-containing derivatives were selected to allow selective and hypersensitive determination with a modified version of the alkali-flame detector. This method comprises the formation of the N-diethyl phosphate amino acid methyl esters and subsequent gas-chromatographic separation and analysis. The minimum detectable limit for alanine (response-noise, 2:1) was found to be ca. 5 × 10−12 g injected. The method should be applicable to the investigation of very small amounts of naturally occurring amino acids and peptides, as was shown with gramicidin-S. A gas-chromatographic analysis of 250 pg of gramicidin-S was found to yield clearly discernible peaks for valine, leucine, proline, and phenylalanine.