title: Capillary electrophoretic analysis of gamma-aminobutyric acid and alanine in tea with in-capillary derivatization and fluorescence detection.
abstract: The aim of this study was to investigate an in-capillary derivatization capillary electrophoresis (CE) technique that was performed to determine the concentration of gamma-aminobutyric acid (GABA) and alanine (Ala) in tea after being derivatized with o-phthaldialdehyde/2-mercaptoethanol (OPA/2-ME) to form fluorescence-labeled products. The conditions of labeled derivatization and CE separation were optimized and then applied to real sample analysis. The labeled derivatization with 20 mM OPA and 26.67 mM 2-ME (mol ratio=0.75) at pH 10 offered the most sensitive detection, and the separation with 30 mM sodium tetraborate buffer (pH 10.0) under 21 kV achieved good selectivity within 14 min. The detections were linear in the range of 0.05-5 microM with correlation coefficients (R2) of 0.9995 and 0.9964 and with detection limits of 0.004 and 0.02 microM for GABA and Ala, respectively. The recoveries were 94.22% (3.58% RSD) and 93.54% (6.46% RSD) for five determinations of GABA and Ala, respectively. This method is a fast, convenient, sensitive, and eco-friendly way to determine the GABA and Ala in tea samples from different manufacturing processes.
authors.affiliation: Department of Chemistry, National Chung Hsing University, Taichung 402, Taiwan.
authors.forename: Yar-Ping
authors.initials: YP
authors.lastname: Lin
authors.forename: Yi-Song
authors.initials: YS
authors.lastname: Su
authors.forename: Jen-Fon
authors.initials: JF
authors.lastname: Jen
mesh_terms: D000409:Alanine / Q000032:analysis*; D019075:Electrophoresis, Capillary / Q000379:methods*; D007202:Indicators and Reagents; D008623:Mercaptoethanol; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013662:Tea / Q000737:chemistry*; D005680:gamma-Aminobutyric Acid / Q000032:analysis*; D009764:o-Phthalaldehyde
chemical_list: D007202:Indicators and Reagents; D013662:Tea; D005680:gamma-Aminobutyric Acid; D008623:Mercaptoethanol; D009764:o-Phthalaldehyde; D000409:Alanine