Graduate School of Pharmaceutical Sciences, Kyushu University, 3-1-1 Maidashi, Higasi-ku, Fukuoka 812-8582, Japan.
KAGAMI Inc., 7-7-15 Saito-asagi, Ibaraki 567-0085, Japan.
J Chromatogr A. 2020 Aug 16;1625:461255. doi: 10.1016/j.chroma.2020.461255. Epub 2020 May 31.
A three-dimensional (3D) HPLC system in combination with fluorescence derivatization has been developed for the highly sensitive and selective analysis of chiral amino acids in extraterrestrial samples. As the targets, alanine (Ala), 2-aminobutyric acid (2AB), valine (Val), norvaline (nVal) and isovaline (iVal), frequently found chiral amino acids in the carbonaceous chondrites, were selected. These amino acids were pre-column derivatized with 4-fluoro-7-nitro-2,1,3-benzoxadiazole (NBD-F), and the target analytes were separated from other amino acids and organic compounds by a reversed-phase column in the first dimension. The targets were further separated from interferences by an anion-exchange column in the second dimension, and their enantiomers were separated and determined in the third dimension by a Pirkle-type enantioselective column. The present 3D-HPLC system was validated and applied to the Murchison meteorite and the Antarctic meteorites, and all of the target amino acid enantiomers were clearly observed (0.78-22.33 nmol/g in the Murchison meteorite and 1.79-78.84 nmol/g in the Antarctic meteorites) without severe interferences. The %L values of the non-proteinogenic amino acids were almost 50% in both meteorites, and even the proteinogenic amino acids were almost racemic in the Antarctic meteorites.
已开发出一种三维（3D）高效液相色谱系统，结合荧光衍生化方法，用于对外星样品中手性氨基酸进行高灵敏度和选择性分析。作为目标物，选择了在碳质球粒陨石中常见的手性氨基酸：丙氨酸（Ala）、2-氨基丁酸（2AB）、缬氨酸（Val）、正缬氨酸（nVal）和异缬氨酸（iVal）。这些氨基酸在柱前与 4-氟-7-硝基-2,1,3-苯并恶二唑（NBD-F）衍生化，目标分析物在第一维通过反相柱从其他氨基酸和有机化合物中分离出来。在第二维通过阴离子交换柱进一步将目标物与干扰物分离，在第三维通过 Pirkle 型手性选择性柱分离和测定其对映异构体。本 3D-HPLC 系统经过验证后，应用于默奇森陨石和南极陨石，均清晰观察到所有目标氨基酸对映体（默奇森陨石中为 0.78-22.33 nmol/g，南极陨石中为 1.79-78.84 nmol/g），且无严重干扰。非蛋白氨基酸的 %L 值在两种陨石中几乎都为 50%，甚至南极陨石中的蛋白氨基酸几乎也是外消旋的。
