BS ISO 14502-2-2005 Determination of substances characteristic of green and black tea - Content of catechins in green tea - Method using high-performance liquid chromatography《绿茶和红.pdf
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1、BRITISH STANDARDBS ISO 14502-2:2005Incorporating Corrigendum No. 1 Determination of substances characteristic of green and black tea Part 2: Content of catechins in green tea Method using high-performance liquid chromatographyICS 67.140.10g49g50g3g38g50g51g60g44g49g42g3g58g44g55g43g50g56g55g3g37g54g
2、44g3g51g40g53g48g44g54g54g44g50g49g3g40g59g38g40g51g55g3g36g54g3g51g40g53g48g44g55g55g40g39g3g37g60g3g38g50g51g60g53g44g42g43g55g3g47g36g58BS ISO 14502-2:2005This British Standard was published under the authority of the Standards Policy and Strategy Committee on 7 April 2005 BSI 2006ISBN 0 580 4577
3、7 XNational forewordThis British Standard reproduces verbatim ISO 14502-2:2005, including Technical Corrigendum April 2006 and implements it as the UK national standard.The UK participation in its preparation was entrusted to Technical Committee AW/8, Tea, which has the responsibility to: aid enquir
4、ers to understand the text; present to the responsible international/European committee any enquiries on the interpretation, or proposals for change, and keep UK interests informed; monitor related international and European developments and promulgate them in the UK.A list of organizations represen
5、ted on this committee can be obtained on request to its secretary.Cross-referencesThe British Standards which implement international publications referred to in this document may be found in the BSI Catalogue under the section entitled “International Standards Correspondence Index”, or by using the
6、 “Search” facility of the BSI Electronic Catalogue or of British Standards Online.This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. Compliance with a British Standard does not of itself confer immunity from leg
7、al obligations.Summary of pagesThis document comprises a front cover, an inside front cover, the ISO title page, pages ii to iv, pages 1 to 23 and a back cover.The BSI copyright notice displayed in this document indicates when the document was last issued.Amendments issued since publicationAmd. No.
8、Date Comments16366Corrigendum No. 131 July 2006 Changes to Clauses 4.10.1, 9.1, 9.2.3 and Annex E, Table E.2Reference numberISO 14502-2:2005(E)INTERNATIONAL STANDARD ISO14502-2First edition2005-03-01Determination of substances characteristic of green and black tea Part 2: Content of catechins in gre
9、en tea Method using high-performance liquid chromatography Dtermination des substances caractristiques du th vert et du th noir Partie 2: Dosage des catechins dans le th vert Mthode par chromatographie en phase liquide haute performance BS ISO 145022:2005ii BS ISO 145022:2005iiiContents Page Forewor
10、d iv 1 Scope 1 2 Normative references . 1 3 Principle . 1 4 Reagents 1 5 Apparatus. 5 6 Sampling 5 7 Preparation of test samples. 6 8 Procedure. 6 8.1 General. 6 8.2 Determination of dry matter content. 6 8.3 Test portion . 6 8.4 Extraction of polyphenols 6 8.5 Dilution. 7 8.6 Determination 7 9 Calc
11、ulation. 8 9.1 General. 8 9.2 Quantitation using catechin standards 8 9.3 Quantitation using a caffeine standard and catechin Relative Response Factors (RRFs) . 9 10 Precision 10 10.1 Interlaboratory test . 10 10.2 Repeatability 10 10.3 Reproducibility 10 11 Test report 10 Annex A (informative) Resu
12、lts of interlaboratory tests 11 Annex B (informative) Assessment of purity of standards 13 Annex C (informative) Typical HPLC chromatograms 14 Annex D (informative) The effect of ferric ions on catechin RRFs 18 Annex E (informative) Quantitative comparison Use of catechin standards or a caffeine sta
13、ndard in conjunction with catechin RRFs. 21 Bibliography . 23 BS ISO 145022:2005iv Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out throu
14、gh ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collabora
15、tes closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2. The main task of technical committees is to prepare International Standar
16、ds. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. Attention is drawn to the possibility that some of the elements of th
17、is document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. ISO 14502-2 was prepared by Technical Committee ISO/TC 34, Food products, Subcommittee SC 8, Tea. ISO 14502 consists of the following parts, under the general title Deter
18、mination of substances characteristic of green and black tea: Part 1: Content of total polyphenols in tea Colorimetric method using Folin-Ciocalteu reagent Part 2: Content of catechins in green tea Method using high-performance liquid chromatography BS ISO 145022:20051Determination of substances cha
19、racteristic of green and black tea Part 2: Content of catechins in green tea Method using high-performance liquid chromatography 1 Scope This part of ISO 14502 specifies a high-performance liquid chromatographic (HPLC) method for the determination of the total catechin content of tea from the summat
20、ion of the individual catechins. It is applicable to both leaf and instant green tea, and with precision limitations to black tea (see Annex A). Gallic acid and caffeine can also be determined by this method, as can theogallin and theaflavins. 2 Normative references The following referenced document
21、s are indispensable for the application 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 Preparation of ground sample of known dry matter content ISO 3696:19
22、87, Water for analytical laboratory use Specification and test methods ISO 7513, Instant tea in solid form Determination of moisture content (loss in mass at 103 C) 3 Principle The total catechin content from a test portion of finely ground leaf tea is extracted with 70 % methanol at 70 C. Instant t
23、eas are dissolved in hot water with 10 % (volume fraction) acetonitrile added to stabilize the extract. The individual catechins in the extract are determined by HPLC on a phenyl-bonded column using gradient elution with UV detection at 278 nm. External standards are used for quantitation. External
24、catechin standards of defined purity and moisture content may be used directly. Alternatively, caffeine may be used as a standard in conjunction with individual catechin Relative Response Factors (RRFs) established by an ISO international interlaboratory test. 4 Reagents Use only reagents of recogni
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