G.S. Shephard

Determination of plasma amino acids by gas chromatography

A complete methodology, incorporating a novel clean-up technique, for quantitative determination of amino acids in plasma by gas chromatography is described. Glucose, a component causing major analytical interference, is removed by an enzymic reaction included in the pre-chromatographic clean-up. The procedure for derivatisation of amino acid standards is shown to be reproducible down to a level of 2.5 micrograms for each amino acid, relative standard deviations for all amino acids except arginine and histidine being 3% or lower. For the entire procedure applied to plasma, relative standard deviations for most amino acids are below 5% with recoveries ranging from 90 to 120%. Normal values, obtained using eighteen plasma samples, are in reasonable agreement with published data. Plasma amino acid values were determined simultaneously by gas chromatographic and ion-exchange chromatographic techniques. Statistical evaluation shows there to be no significant difference between corresponding values for eleven amino acids. Values for tyrosine, histidine and particularly phenylalanine show significant differences (p less than 0.001).

Gas chromatographic analysis of amino acids in physiological fluids: a critique

The available methodology for sample purification prior to gas chromatographic analysis of amino acids in physiological fluids and tissue extracts is analysed. It would appear that over the past ten years the method of choice is that of an ion-exchange purification step, and little, if any, progress has been achieved in sample purification procedures. The inherent disadvantages of such a methodology are not only perpetuated but also cast some considerable doubt on the accuracy of the quantitative analysis of amino acids.

Gas-liquid chromatography of amino acids with Supelcoport as solid support

Influence du support sur la separation, le Chromosorb W-HP est superieur pour cette separation