title: Direct determination of free amino acids and sugars in green tea by anion-exchange chromatography with integrated pulsed amperometric detection.
abstract: Determination of amino acids and sugars in green tea by anion-exchange chromatography with integrated pulsed amperometric detection was developed. Amino acids and sugars were separated on an anion-exchange column at a flow-rate of 0.25 ml/min by using ternary gradient elution consisting of deionized water, 0.25 M sodium hydroxide, and 1.0 M sodium acetate. Under optimized conditions, theanine was separated from glutamine and three sugars (glucose, fructose, and sucrose) were eluted earlier than the neutral amino acids to avoid their interference with each other. RSDs of the peak area of analytes were lower than 4.6%. Detection limits for the analytes ranged from 0.12 to 4.9 pmol. The linearities for all analytes were two or three orders of magnitude with the correlation coefficients greater than 0.99. This method was applied to determination of amino acids and sugars in green tea with satisfactory results.
authors.affiliation: Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, P.O. Box 2871, Beijing 100085, China.
authors.forename: Yongsheng
authors.initials: Y
authors.lastname: Ding
authors.forename: Hong
authors.initials: H
authors.lastname: Yu
authors.forename: Shifen
authors.initials: S
authors.lastname: Mou
mesh_terms: D000596:Amino Acids / Q000032:analysis*; D000837:Anion Exchange Resins; D002241:Carbohydrates / Q000032:analysis*; D002852:Chromatography, Ion Exchange / Q000379:methods*; D004563:Electrochemistry / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013662:Tea / Q000737:chemistry*
chemical_list: D000596:Amino Acids; D000837:Anion Exchange Resins; D002241:Carbohydrates; D013662:Tea