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Separation and detection of free D- and L-amino acids in tea by off-line two-dimensional liquid chromatography

Abstract

D-amino acids are currently paid attention as new physiologically active substances. Foodstuffs and beverages containing D-amino acids are the matter of interest. Until now, the profile of D-amino acids has not been reported in natural and fermented teas except for theanine. In this study, an off-line 2D-HPLC method combining a Gemini C18 column and a CHIRALPAKĀ® IC-3 column or a self-prepared poly (MQD-co-HEMA-co-EDMA) monolithic capillary column was employed for the separation and detection of D-amino acids in tea samples with the co-existence of large amount of L-amino acids. The free amino acids fractions in Longjing, Black, Oolong, and Pu-erh tea samples were separated and collected after pre-column derivatization using 9-fluorenylmethoxycarbonyl (FMOC) chloride by the reversed-phase mode, then were concentrated and separated to D- and L-form on chiral column. Among them, the D-form of isoleucine (Ile) (1.0-1.6%), alanine (Ala) (0.1-0.8%), phenylalanine (Phe) (0.1-0.4%), valine (Val) (0.2-0.3%), serine (Ser) (0.1-0.2%), aspartic acid (Asp) (0.2%), proline (Pro) (0.1%) were detected in Longjing and Oolong teas. Differences between natural tea and fermented tea in profiles of D-amino acids as well as the total amino acids were also observed. The results provided the useful information for the bio-function research of D-amino acids in tea.

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Publication details

The article was received on 26 Jun 2017, accepted on 02 Oct 2017 and first published on 03 Oct 2017


Article type: Paper
DOI: 10.1039/C7AY01569K
Citation: Anal. Methods, 2017, Accepted Manuscript
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    Separation and detection of free D- and L-amino acids in tea by off-line two-dimensional liquid chromatography

    X. Wang, H. Wu, R. Luo, D. Xia, Z. Jiang and H. Han, Anal. Methods, 2017, Accepted Manuscript , DOI: 10.1039/C7AY01569K

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