Simplified procedure for specific determination of imino acids in human blood plasma by high-performance liquid chromatography.

After deproteinization with 70% aqueous ethanol and evaporation to dryness, a plasma sample was subjected to the formol reaction. Then Dns derivatization of imino acids was carried out for 20 min at 37 degrees C. An aliquot of the resulting solution was subjected to reversed-phase chromatography using continuous gradient elution with acetonitrile-50 mM acetate buffer (pH 4.0) as solvent system. This method is selective for imino acids. Hydroxyproline and proline levels could be determined using 30 microliter of plasma.