Simultaneous determination of amino acids in tea leaves by micellar electrokinetic chromatography with laser-induced fluorescence detection.
A rapid and effective method of micellar electrokinetic chromatography with laser-induced fluorescence detection was developed for the simultaneous determination of amino acids in tea leaves. Pre-column derivatization of the analytes used 4-chloro-7-nitrobenzofurazan (NDB-Cl). Optimal separation was achieved at +20kV using an uncoated fused silica capillary (40.0cm effective length, 50.2cm total length, 75μm internal diameter), as well as 20mM sodium borate (pH 8.5), 20mM Brij 35, and acetonitrile 10% (v/v) as running buffers. Within 11min, 15 amino acids were separated completely. The optimized method demonstrated good linearity (r(2)⩾0.9990), precision (⩽6.65%), accuracy (85.50-112.74%), and sensitivity (0.1ng/mL-100ng/mL). The method successfully determined the quantity of amino acids in five different tea leaves; furthermore, theanine was identified as the most abundant amino acid in teas. The proposed method showed great potential in further investigations on the biofunctions of different tea samples.
College of Chemical Engineering, Sichuan University, Chengdu, China.
Jin
J
Yan
Yuanli
Y
Cai
Yufei
Y
Wang
Xia
X
Lin
Hui
H
Li
D000596:Amino Acids / Q000737:chemistry*; D028241:Camellia sinensis / Q000737:chemistry*; D020374:Chromatography, Micellar Electrokinetic Capillary / Q000379:methods*; D018515:Plant Leaves / Q000737:chemistry*; D013050:Spectrometry, Fluorescence / Q000379:methods*
D000596:Amino Acids
Amino acids; Laser-induced fluorescence; Micellar electrokinetic chromatography; Tea