title: Rapid determination of underivatized pyroglutamic acid, glutamic acid, glutamine and other relevant amino acids in fermentation media by LC-MS-MS.
abstract: Determination of amino acids in a complex matrix without derivatization is advantageous, however, difficulties are found in both the detection and the separation of those compounds. In this study, a rapid and reliable LC-MS-MS method for the quantitation of underivatized amino acids in exocellular media was established. Injections were made directly after centrifugation of the samples, without further preparation. The separation of seven underivatized amino acids was achieved on a reversed-phase C18 column with pentadecafluorooctanoic acid as a volatile ion-pair reagent, and the specific detection of most amino acids was achieved by MS-MS of the specific transitions [M + H]+-->[M + H - 46]+. The calibration curves of all analytes were linear over the range of 1.0-1000 microg ml(-1) and the detection limits ranged from 0.1 to 5 ng ml(-1), with an injection volume of 20 microl. The inter-day and intra-day precisions ranged from 2.6 to 5.7% and 4.8 to 8.2%, respectively; the mean recoveries of the seven analytes were 81-104%, 91-107% and 93-101% respectively at the spiked level of 10, 40 and 200 microg ml(-1). A large number of fermentation samples were analysed using this method. The technique is simple, rapid, selective and sensitive, and shows potential for the high-throughput quantitation of amino acids from other biological matrices.
authors.affiliation: Analysis Center, School of Life Science and Engineering, Tsinghua University, Beijing, China.
authors.forename: Jun
authors.initials: J
authors.lastname: Qu
authors.forename: Wei
authors.initials: W
authors.lastname: Chen
authors.forename: Guoan
authors.initials: G
authors.lastname: Luo
authors.forename: Yiming
authors.initials: Y
authors.lastname: Wang
authors.forename: Shengyuan
authors.initials: S
authors.lastname: Xiao
authors.forename: Zhihua
authors.initials: Z
authors.lastname: Ling
authors.forename: Guoqiang
authors.initials: G
authors.lastname: Chen
mesh_terms: D000596:Amino Acids / Q000032:analysis*; D019149:Bioreactors; D002853:Chromatography, Liquid / Q000379:methods; D003352:Corynebacterium / Q000378:metabolism; D003470:Culture Media / Q000737:chemistry*; D005285:Fermentation; D018698:Glutamic Acid / Q000032:analysis; D005973:Glutamine / Q000032:analysis; D013058:Mass Spectrometry / Q000379:methods; D011761:Pyrrolidonecarboxylic Acid / Q000032:analysis
chemical_list: D000596:Amino Acids; D003470:Culture Media; D005973:Glutamine; D018698:Glutamic Acid; D011761:Pyrrolidonecarboxylic Acid