Rapid high-throughput assay for the measurement of amino acids from microdialysates and brain tissue using monolithic C18-bonded reversed-phase columns

A rapid precolumn high-performance liquid chromatography method based on fluorescence detection has been developed for the measurement of multiple amino acids from both ex vivo and in vivo biological samples using monolithic C18 columns. A mixture of 18 primary amino acids were derivatised with napthalene-2,3-dicarboxaldehyde (NDA) in the presence of cyanide. The resulting isoindole derivatives were resolved within 10 min using a linear binary gradient elution profile with Rs values in the range 1.2–9.0. The limit of detection (LOD) was found to be between 6.0 and 60 fmol for 5 μl injection with a signal to noise ratio of 3:1. The NDA derivatives were found to be stable for 9 h at 4 °C. This assay has been employed for the rapid analysis of amino acids from brain tissue and microdialysis samples. Examples of application of the method are given.