A Facile and High-Sensitivity Method for Determining Proteinogenic Amino Acid Enantiomers by Integrating Chiral Phosphinate Derivatizing, 31 P NMR and Parallel Reaction Monitoring.

Here, we have documented a new protocol to determine d/l-amino acids by derivatizing amino acids via a chiral phosphinate. ( R P )-l-Menthyl phenylphosphinate was able to bond both primary and secondary amines, as well as improve the sensitivity of analytes in MS. Eighteen pairs of amino acids were successfully labeled except for Cys which has a thiol group on the side chain, and the chirality of amino acids can be discriminated by 31 P NMR. Seventeen pairs of amino acids were separated by a C18 column within 45 min of elution, and resolution values ranged from 2.01 to 10.76. The lowest limit of detection was 10 pM acquired at parallel reaction monitoring, in which two factors collectively contributed that the ability of protonation of phosphine oxide and the sensitivity of parallel reaction monitoring. Chiral phosphine oxides might be a promising tool in future chiral metabolomics.