Simultaneous determination of all aminobutyric acids by chiral derivatization and liquid chromatography-tandem mass spectrometry

Aminobutyric acids include eight structural or stereoisomers that exhibit a wide range of biological activities. Recent evidence on some low abundant isomers have increased the demand for highly selective analysis of all the isomers; however, simultaneous separation of all the aminobutyric acid isomers has not been successful yet, except for a specialized method that uses multiple separation columns and a split of samples. In this study, we developed a new analytical method using chiral derivatization and liquid chromatography-tandem mass spectrometry to separate all the aminobutyric acid isomers in a single separation column. All the diastereomeric derivatives were resolved in a C18 column, and the derivatives showed characteristic fragmentation patterns in tandem mass spectrometry. By using the method, we analyzed the isomers in the Arabidopsis thaliana seeds and revealed the existence of three low abundant isomers, i.e., d-, l-beta-aminoisobutyric acid, and d-beta-aminobutyric acid. The proposed method uses a commercially available chiral derivatizing reagent and a broadly used column; therefore, it can be widely used in biological and food analyses.