J RYKL¹, A JAFFUEL<sup>2

1</sup>Shimadzu Schweiz GmbH, ²Shimadzu France

Amino acids are routinely assayed to diagnose inherited metabolism disorders. As they are highly polar compounds, they are hardly retained onto reverse phase columns. Derivatization or addition of ion pairing reagent in the mobile phase is required. For easier and rugged analysis of amino acids, there was a need for a new solution not using pre-mentioned reagents. In this context, a new LC-MS/MS method was developed, for the simultaneous high sensitive quantification of 49 amino acids, using a mixed-mode column (hydrophilic and ion exchange interactions) and typical volatile mobile phase suitable for LC-MS. Sample preparation was very simple. Plasma was precipitated and supernatant was directly injected. All amino acids were separated within 15 minutes. Particular attention was paid to separate isobaric amino acids chromatographically or by using specific MRM transitions. Plasma control samples showed good repeatability,stability and accuracy. The method proved its fits for purpose to support diagnostics and may be used also in clinical studies to monitor drug effects on metabolism.