Determination of 35 Free Amino Acids in Tea Using Ultra-Performance Liquid Chromatography Coupled With Quadrupole Time-of-Flight Mass Spectrometry.

Jian Li,Hongyu Ma,Lixin Fan,Qiang Li,Junmei Ma,Lei Zheng,Sufang Fan,Yan Zhang

doi:10.3389/fnut.2021.767801

Abstract

The purpose of this research was to develop a simple, sensitive, and accurate method for simultaneous determination of 35 free amino acids using ultra-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF/MS). Tea samples were extracted with boiling water bath, and then separated by XBridge BEH Amide column by gradient elution. The exact mass and MS/MS spectra of the target compound was detected under the TOF–MS and Information dependent acquisition (IDA)–MS/MS mode. The results demonstrated good linearity (R2 > 0.9980) in the range of 0.5–1,000 ng/mL. The limits of detection (LODs) were 0.13–25.00 mg/kg and the limits of quantitation (LOQs) were 0.25–50.00 mg/kg. The recovery rate ranged from 70.1 to 105.1% with relative standard deviations (RSDs) <11% (n = 6). This research provides a targeted strategy for developing an analysis method for amino acids in tea.

Highlights

Tea, which originated in China, is one of the most popular and widely consumed beverage in the world because of its refreshing taste, attractive aroma, and potential health benefits [1]
Sample Preparation Refer to GB/T 8312-2013 [36] for sample preparation: 0.5 g crushed tea was weighed into a 500 mL breaker followed by addition of 4.5 g magnesium oxide and 250 mL boiling water
The results showed that 35 amino acids had higher response in positive mode, and so the positive mode was used for detection in this study

Summary

Introduction

Tea, which originated in China, is one of the most popular and widely consumed beverage in the world because of its refreshing taste, attractive aroma, and potential health benefits [1]. There has been extensive research on the valorization and health benefits of medicinal plants (in general) and teas (in particular), but systematic and in-depth research on the chemical components of flavor in tea is still weak in China [2]. Amino acids and other molecules such as carotenoids, fatty acids,glycosides, and sugars contribute to the aroma in teas [3, 4]. Free amino acids play an important role in the chemical composition of tea [5], which is one of the important evaluation factors of tea quality [6]. Amino acids are the basic units of proteins, which are the important components

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Conclusion