Rapid and selective quantification of l-theanine in ready-to-drink teas from Chinese market using SPE and UPLC-UV

Chen, Guoqiang; Wang, Yun; Song, Weiqi; Zhao, Bo; Dou, Yuling

doi:10.1016/j.foodchem.2012.04.084

Cited by 11 publications

(4 citation statements)

References 25 publications

(33 reference statements)

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“…As reported by Chen et al[36], UPLC analysis of tea polyphenols in comparison with HPLC gave superior chromatographic resolution and sensitivity, while reducing analysis time and solvent consumption. Similarly, in the present work, UPLC reduced the time to achieve polyphenol analysis to 11 min against 30 min [3], or 40 min[30] while giving better resolution.…”

mentioning

confidence: 72%

Instant controlled pressure drop texturing for intensifying ethanol solvent extraction of olive (Olea europaea) leaf polyphenols

Mkaouar

Bahloul

Gelicus

et al. 2015

Separation and Purification Technology

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confidence: 72%

Instant controlled pressure drop texturing for intensifying ethanol solvent extraction of olive (Olea europaea) leaf polyphenols

Mkaouar

Bahloul

Gelicus

et al. 2015

Separation and Purification Technology

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“…For instance, glutamic acid has the umami taste and can improve the taste of tea infusions [10,11,12]. In addition, there was a significant positive correlation between tea quality and theanine content [13]. There are two main kinds of amino acids in tea plants: one is the amino acid which composes protein (relatively stable and rarely changes with the external environment); the other is the free amino acid (FAA) (the main form of N storage in tea plants that always change with the environment) [14].…”

Section: Introductionmentioning

confidence: 99%

Characteristics of Free Amino Acids (the Quality Chemical Components of Tea) under Spatial Heterogeneity of Different Nitrogen Forms in Tea (Camellia sinensis) Plants

et al. 2019

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Nitrogen (N) forms are closely related to tea quality, however, little is known about the characteristics of quality chemical components in tea under the spatial heterogeneity of different N forms. In this study, a split-root system, high performance liquid chromatography (HPLC), and root analysis system (WinRHIZO) were used to investigate free amino acids (FAAs) and root length of tea plants under the spatial heterogeneity of different N forms. Uniform. (U.) ammonium (NH4+) (both compartments had NH4+), U. nitrate (NO3−) (both compartments had NO3−), Split. (Sp.) NH4+ (one of the compartments had NH4+), and Sp. NO3− (the other compartment had NO3−) were performed. The ranking of total FAAs in leaves were as follows: U. NH4+ > Sp. NH4+/Sp. NO3− > U. NO3−. The FAA characteristics of Sp. NH4+/Sp. NO3− were more similar to those of U. NO3−. The contents of the important FAAs (aspartic acid, glutamic acid, and theanine) that determine the quality of tea, increased significantly in U. NH4+. The total root length in U. NH4+ was higher than that in the other treatments. More serious root browning was found in U. NO3−. In conclusion, NH4+ improved the accumulations of FAAs in tea leaves, which might be attributed to the root development.

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“…To determine the concentration of compounds by this technique, it is necessary to chemically modify (derivatize) them into derivatives that absorb or fluoresce in the ultraviolet-visible (UV-Vis) wavelength range. Several reagents including but not limited to phenylisothiocyanate (PITC) [15], o-phthaldialdehyde (OPA) [16], 9-fluorenylmethyl chloroformate (Fmoc-Cl) [17,18], naphthalene dicarboxaldehyde (NDA) [19], 5-dimethylamino-1-naphthalenesulfonyl chloride (dansyl-Cl) [20], 4-dimethylaminoazobenzene-4-sulfonyl chloride (dabsyl chloride) [21], 2,4-dinitrofluorobenzene (DNFB) [22], and 6-aminoquinolyl-N-hydroxysuccinimidylcarbamate (AQC) [23] have been used for this purpose.…”

Section: Introductionmentioning

confidence: 99%

Development and Validation of a Simple, Selective, and Accurate Reversed-Phase Liquid Chromatographic Method with Diode Array Detection (RP-HPLC/DAD) for the Simultaneous Analysis of 18 Free Amino Acids in Topical Formulations

et al. 2022

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Even though there are reported methods for the quantification of free amino acids (FAAs) in biological products, no work has been done on the analysis of these substances in formulations. Moreover, further research is required as the reported methods do not fulfill analytical method requirements. The objective of this study was, therefore, to develop and validate a rapid, reliable, and appropriate RP-HPLC/DAD method for the simultaneous determination of 18 FAAs (l-Ala, l-Arg, l-Asn, l-Asp, l-Gln, l-Glu, l-Gly, l-His, l-Ile, l-Lue, l-Lys, l-Met, l-Orn, l-Phe, l-Pro, l-Ser, l-Thr, and l-Val) in topical formulations. After appropriate method development, the technique was validated for selectivity, linearity and range, limit of detection, limit of quantification, precision, and accuracy. The samples were derivatized with 9-fluorenylmethyl chloroformate (Fmoc-Cl). Chromatographic separation was performed on InfinityLab Poroshell 120 E.C 18 (3 × 50) mm, 2.7 μm column at 25 °C. The mobile phase consisting of water and acetonitrile adjusted to appropriate pH was pumped in gradient mode at a flow rate of 0.7 mL/min. Ten microliters were injected and analyte detection was conducted using a DAD. The results indicate that the method was selective for these FAAs. It was linear over the concentration range of 5–80 µM with a correlation coefficient greater than 0.995. Moreover, it was sensitive, precise, accurate, and robust. All the reported drawbacks of RP-HPLC-based analysis of FAAs were resolved, and hence, this new method can be considered appropriate for the analysis of these FAAs in topical formulations.

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Rapid and selective quantification of l-theanine in ready-to-drink teas from Chinese market using SPE and UPLC-UV

Cited by 11 publications

References 25 publications

Instant controlled pressure drop texturing for intensifying ethanol solvent extraction of olive (Olea europaea) leaf polyphenols

Instant controlled pressure drop texturing for intensifying ethanol solvent extraction of olive (Olea europaea) leaf polyphenols

Characteristics of Free Amino Acids (the Quality Chemical Components of Tea) under Spatial Heterogeneity of Different Nitrogen Forms in Tea (Camellia sinensis) Plants

Development and Validation of a Simple, Selective, and Accurate Reversed-Phase Liquid Chromatographic Method with Diode Array Detection (RP-HPLC/DAD) for the Simultaneous Analysis of 18 Free Amino Acids in Topical Formulations

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