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.