Development of a protocol for the automated analysis of amino acids in brain tissue samples and microdialysates

An automated precolumn derivatisation method has been developed for the mea surement of fourteen amino acids in brain tissue and microdialysate samples . The method involves labelling amino acids with naphthalene-2,3-dicarboxal dehyde (NDA) in the presence of cyanide (CN-). The resulting highly stable N-substituted 1-cyanobenz[f]isoindole (CBI) derivatives were separated usin g a binary gradient elution profile and detected fluorometrically. The orde r of elution of the derivatised amino acids was confirmed by using liquid c hromatography with fluorescence and mass spectrometric detection in tandem. Linear calibration plots were obtained for all amino acids in the range st udied (0.2-12.5 mu M). The limit of detection for CBI derivatives of amino acids was in the range 5-20 fmol (S/N=2) using a 5 mu l injection volume. T he method has been used for the measurement of amino acids in microdialysat es from rat brain and tissue homogenates from different regions of mouse br ain. (C) 1999 Elsevier Science B.V. All rights reserved.