GB/T 23193-2017Determination of theanine in tea—Uusing high performance liquid chromatography (English PDF)
茶叶中茶氨酸的测定 高效液相色谱法
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Issued by
SAMR; SAC
Level / Type
National · Recommended
Issue date
November 1, 2017
Implementation date
May 1, 2018
Scope
GB/T 23193-2017 is the English-translated version of 茶叶中茶氨酸的测定 高效液相色谱法.
GB/T 23193-2017 is the Chinese national method for measuring the theanine content of tea by high performance liquid chromatography. The sample is extracted with boiling water, the strongly polar compounds are separated on an RP-18 column, and theanine is detected at 210 nm and quantified against a series of standard solutions.
The standard lists the reagents and their grades, from chromatographic grade acetonitrile and an L-theanine standard of purity not less than 99 % to the mobile phases and the 0.45 µm aqueous filter, with standard solutions from 0.0 mg/mL to 0.20 mg/mL.
The instrument is a liquid chromatograph with gradient elution, a UV detector and a chromatography workstation. It applies to the determination of theanine in tea.
It replaces GB/T 23193-2008, was issued on 1 November 2017 and has applied since 1 May 2018.
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Document preview — GB/T 23193-2017
National Standard of the People's Republic of China
- ICS
- 67.140.10
- Classification
- X 55
- Replacing
- GB/T 23193-2008
Issued by: State Administration for Market Regulation; Standardization Administration of the PRC
Contents
- Foreword
- 1 Scope
- 2 Normative references
- 3 Principle
- 4 Reagent
- 5 Instruments
Foreword
This standard was drafted in accordance with the rules given in GB/T 1.1-2009.
This standard replaces GB/T 23193-2008 "Determination of theanine in tea high performance liquid chromatography." And compared to GB/T 23193-2008, the main technical differences are as follows.
--- Measuring principle and pre-treatment process is completely different;
--- Sample handling differences.0.5g sample water 100mL, 80 °C water bath leaching 45min, modified to 1.0g sample plus boiling water 100mL, extraction 30min;
--- No purification and derivatization steps, after 0.45µm membrane, direct injection.
1 Scope
This standard specifies the method for the determination of theanine content in tea by high performance liquid chromatography.
This standard applies to the determination of theanine in tea.
2 Normative references
The following documents for the application of this document is essential. For dated references, only the dated version applies to this document. For undated references, the latest edition (including all amendments) applies to this document.
GB/T 6682 analytical laboratory water specifications and test methods
GB/T 8302 tea sampling
Preparation of GB/T 8303 tea ground sample and determination of its dry matter content
3 Principle
The theanine in tea samples was extracted by boiling water. After purifying, the RP-18 column was used to separate the strong polar compounds. The detection wavelength 210nm, measured by high performance liquid chromatography, compared with the standard series of qualitative, quantitative.
4 Reagent
4.1 Unless otherwise indicated, the reagents used in the analysis were of analytical grade, water for the three water GB/T 6682 regulations.
4.2 Acetonitrile. Chromatography grade.
4.3 Theanine standard (L-theanine). Purity >= 99%.
4.4 HPLC mobile phase
4.4.1 Mobile phase A
100% pure water.
4.4.2 Mobile phase B
100% acetonitrile (4.2).
4.5 Theanine standard stock solution
4.5.1 Theanine standard stock solution
Weigh 0.05g Theanine (accurate to 0.0001g), dissolved in water and then transferred to 50mL volumetric flask, diluted to the mark, mix, the solution Liquid contains 1 mg of theanine per ml. Valid for one year.
4.5.2 Theanine standard liquid
Respectively accurately draw Theanine standard stock solution (4.5.1) 0.0mL, 0.1mL, 0.2mL, 0.5mL, 1.0mL, 1.5mL, 2.0mL, the volume of water to 10mL to give concentrations of 0.0mg/mL, 0.01mg/mL, 0.02mg/mL, 0.05mg/mL, 0.10 mg/mL, 0.15 mg/mL, 0.20 mg/mL of the theanine standard solution. Valid for one year.
4.6
0.45µm aqueous filter.
5 Instruments
5.1 High performance liquid chromatography with gradient elution, UV detector and chromatography workstation.
......
This preview omits tables, figures, formulas and parts of the technical clauses. The complete document — 15 pages — is available in the English PDF.
Referenced standards
Normative references
Similar standards
Editions of GB/T 23193
| Edition | Title | Revision | Status |
|---|---|---|---|
| GB/T 23193-2017 | Determination of theanine in tea—Uusing high performance liquid chromatography | current edition | Current |
| GB/T 23193-2008 | Determination of theanine in tea—Uusing high performance liquid chromatography | previous edition | Superseded |
This page sells the current edition, GB/T 23193-2017. Earlier editions are listed for reference only.
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Related Standards
GB/T 6682-2008 — Water for analytical laboratory use - Specification and test methods
GB/T 8302-2013 — Tea -- Sampling
GB/T 8303-2013 — Tea -- Preparation of ground sample and determination of dry matter content
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