Chiral chromatographic analysis of amino acids with pre-column derivatization by <i>o</i>-phthalaldehyde: improving the determination of enantiomers using ion-pair reagents

The development of effective and accessible methods for the chiral analysis of amino acids is an important scientific and practical necessity. One of the most common and convenient techniques is the chromatographic determination of individual enantiomers of amino acids with preliminary conversion of enantiomers into diastereomers, which can then be separated on conventional achiral columns. We have shown that by adding ion-pair reagents to the eluent and varying their structure, one can regulate the efficiency of a chiral amino acid analysis based on the chromatographic determination and resolution of the diastereomeric isoindoles obtained upon pre-column derivatization of amino acids by o-phthalaldehyde in the presence of N-acetyl-L-cysteine. The use of ion-pair reagents allows one to achieve a better resolution of diastereomeric isoindole peaks, while the analysis time can be reduced by increasing the ionic strength. Hence, adding ionpair reagents and optimizing the mobile phase composition are useful approaches in the engineering of an amino acid chiral analysis, along with the synthesis of new chiral SH compounds and the choice of stationary phases.