PRECOLUMN DEPROTEINIZATION METHOD OF HUMAN PLASMA USING A HYDROXYAPATITE CARTRIDGE FOR HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHIC AMINO-ACID-ANALYSIS

Determination of amino acids in human plasma was performed by postcolumn ninhydrin derivatization liquid chromatography using a hydroxyatite cartridge for precolumn deproteinization. This method was suitable for the determination of amino acids in human plasma. The proposed method was simple, rapid (deproteinization time: within 1 min) and reproducible (relative standard deviation: ca. 0.4 to 5.4% (n=3)). Average recovery of 22 amino acids was over 80%. It took about 2 h to elute the amino acids in human plasma on the chromatogram completely. Protein-binding tryptophan was also determined by the proposed method.