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ISO 19563:2017 pdf free

ISO 19563:2017 pdf free.Determination of theanine in tea and instant tea in solid form using high-performance liquid chromatography
This document specifies a high-performance liquid chromatographic (HPLC) method for the determination of theanine content in tea (Camellia sinensis). It is applicable to both tea and instant tea samples. Separation of L- and D-theanine is not possible using this method; however, the L- enantiomer is the major form in tea.
The following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 1572, Tea一Preparation of ground sample of known dry matter content
ISO 1573, Tea一Determination of loss in mass at 103 °C
ISO 1839, Tea一Sampling
ISO 3696, Water for analytical laboratory use一Specification and test methods
ISO 7513, Instant tea in solid form一Determination of moisture content (loss in mass at 103 °C)
ISO 7516, Instant tea in solid form一Sampling
No terms and definitions are listed in this document.
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A reversed-phase (RP)-C18 column is used which is capable of separating more polar compounds using water as an eluent and UV detection at 210 nm. Theanine is separated from the other amino acids;however, the potential co-elution of theanine with methionine is not relevant due to the very small concentration of methionine in tea. It is recommended that polyamide column extract clean-up is used to remove interfering polyphenols for column protection when separation of theanine from other constituents in the extract sample is difficult. Alternatively, the column should be washed after each tea
sample using acetonitrile.
Once the flow rate of the mobile phase (5.6) and temperature [see 9.4.1 c] are stable, condition the column with a blank gradient run (9.4.1). Then inject onto the column 20 μl of each of the standard working solutions (5.7.2), followed by an equal volume of the sample solution ( or the injection of the mixed working standard solutions (5.7.2) at regular intervals (typically after six test solutions). Collect data using the data collection/integration system of the HPLC (6.5) for the peak of theanine in the standard and test sample solutions.ISO 19563 pdf download.

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