1、DRAFT FOR DEVELOPMENT DDENV 12141:1997 Method for Determination of stable oxygen isotope ratio ( 18 O/ 16 O) of water from fruit juices, using isotope ratio mass spectrometry ICS67.160.20DD ENV 12141:1997 This Draft for Development, having been prepared under the direction of the Consumer Products a
2、nd Services Sector Board, was published under the authority of the Standards Board and comes into effect on 15 February1997 BSI12-1998 The following BSI reference relates to the work on this Draft for Development: Committee reference AW/21 ISBN058027019 X Committees responsible for this Draft for De
3、velopment The preparation of this Draft for Development was entrusted to Technical Committee AW/21, Fruit and vegetable juices, upon which the following bodies were represented: British Fruit Juice Importers Association British Retail Consortium British Soft Drinks Association Limited Campden and Ch
4、orleywood Food Research Association Department of Trade and Industry (Laboratory of the Government Chemist) Leatherhead Food Research Association Ministry of Agriculture, Fisheries and Food Royal Society of Chemistry Amendments issued since publication Amd. No. Date CommentsDD ENV 12141:1997 BSI 12-
5、1998 i Contents Page Committees responsible Inside front cover National foreword ii Foreword 2 Text of ENV 12141 3 List of references Inside back coverDD ENV 12141:1997 ii BSI 12-1998 National foreword This Draft for Development has been prepared by Technical Committee AW/21, and is the English lang
6、uage version of ENV12141:1996 Fruit and vegetable juices Determination of the stable oxygen isotope ratio ( 18 O/ 16 O) of water from fruit juices Method using isotope ratio mass spectrometry, published by the European Committee for Standardization (CEN). ENV12141:1996 was produced as a result of in
7、ternational discussions in which the United Kingdom took an active part. This publication is not to regarded as a British Standard It is being issued in the Draft for Development series of publications and is of a provisional nature. It should be applied on this provisional basis so that information
8、 and experience of its practical application may be obtained. Comments arising from the use of this Draft for Development are requested so that UK experience can be reported to the European organization responsible for its conversion to a European Standard. A review of this publication will be initi
9、ated2 years after its publication by the European organization so that a decision can be taken on its status at the end of its3-year life. The commencement of the review period will be notified by an announcement in BSI Update. According to the replies received by the end of the review period, the r
10、esponsible BSI Committee will decide whether to support the conversion into a European Standard, to extend the life of the prestandard or to withdraw it. Comments should be sent in writing to the Secretary of BSI Technical Committee AW/21 at BSI,389 Chiswick High Road, London W44AL, giving the docum
11、ent reference and clause number and proposing, where possible, an appropriate revision of the text. Cross-references ISO5725:1986, to which informative reference is made in the text, has been superseded by ISO5725-1:1994, ISO5725-2:1994, ISO5725-3:1994, ISO5725-6:1994 and ISO5725-6:1994, which are i
12、dentical with the following Parts of BSISO5725 Accuracy (trueness and precision) of measurement methods and results: BS ISO5725-1:1994 General principles and definitions BS ISO5725-2:1994 Basic method for the determination of repeatability and reproducibility of a standard measurement method BS ISO5
13、725-3:1994 Intermediate measures of the precision of a standard measurement method BS ISO5725-4:1994 Basic method for the determination of the trueness of a standard measurement method BS ISO5725-6:1994 Use in practice of accuracy values Summary of pages This document comprises a front cover, an ins
14、ide front cover, pages i and ii, theEN title page, pages 2 to 6, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on theinside front cover.EUROPEAN PRESTANDARD PRNORME EU
15、ROPENNE EUROPISCHE VORNORM ENV12141 October1996 ICS67.160.20 Descriptors: Food products, beverages, fruit and vegetable juices, chemical analysis, determination, ratios, isotopes, oxygen, mass spectrometry English version Fruit and vegetable juices Determination of the stable oxygen isotope ratio (
16、18 O/ 16 O) of water from fruit juices Method using isotope ratio mass spectrometry Jus de fruits et de lgumes Dtermination du rapport des isotopes stables en oxygne ( 18 O/ 16 O) dans leau des jus de fruits Mthode utilisant la spectromtrie de masse des rapports isotopiques Frucht und Gemsesfte Best
17、immung des Verhltnisses der stabilen Sauerstoff-Isotope ( 18 O/ 16 O) im Wasseranteil von Fruchtsften Verfahren unter Verwendung der Isotopenverhltnis Massenspektrometrie This European Prestandard (ENV) was approved by CEN on1996-02-29 as a prospective standard for provisional application. The perio
18、d of validity of this ENV is limited initially to three years. After two years the members of CEN will be requested to submit their comments, particularly on the question whether the ENV can be converted into an European Standard (EN). CEN members are required to announce the existance of this ENV i
19、n the same way as for an EN and to make the ENV available promptly at national level in an appropriate form. It is permissible to keep conflicting national standards in force (in parallel to the ENV) until the final decision about the possible conversion of the ENV into an EN is reached. CEN members
20、 are the national standards bodies of Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom. CEN European Committee for Standardization Comit Europen de Normalisation Europisches
21、Komitee fr Normung Central Secretariat: rue de Stassart 36, B-1050 Brussels 1996 Copyright reserved to CEN members Ref. No. ENV12141:1996 EENV 12141:1996 BSI 12-1998 2 Foreword This European Prestandard has been prepared by the Technical Committee CEN/TC174 “Fruit and vegetable juices Methods of ana
22、lysis” of which the secretariat is held by AFNOR. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are required to announce the existence of this European Prestandard: Austria, Belgium, Denmark, Finland, France, Germany, Greece, Icela
23、nd, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and the United Kingdom. Contents Page Foreword 2 1 Scope 3 2 Normative references 3 3 Symbols and abbreviations 3 4 Principle 3 5 Reagents 3 6 Apparatus 3 7 Procedure 3 8 Calculation 4 9 Precision 4 10 Test rep
24、ort 4 Annex A (informative) Bibliography 5 Annex B (informative) Statistical results of the interlaboratory test 5 Table B.1 5ENV 12141:1996 BSI 12-1998 3 1 Scope This European Prestandard specifies a method for the determination of the stable oxygen isotope ratio ( 18 O/ 16 O) of water from fruit j
25、uices by isotope ratio mass spectrometry (IRMS). 2 Normative references This European Prestandard incorporates by dated or undated reference, provisions from other publications. These normative references are cited at the appropriate places in the text and the publications are listed hereafter. For
26、dated references, subsequent amendments to or revisions of any of these publications apply to this European Prestandard only when incorporated in it by amendment or revision. For undated references the latest edition of the publication referred to applies. ISO5725:1986, Precision of the test methods
27、-Determination of repeatability and reproducibility for a standard test method by inter-laboratory tests. 3 Symbols and abbreviations For the purposes of this Standard, the following symbols and abbreviations apply: 4 Principle The measurement of 18 O/ 16 O ratios are obtained on carbon dioxide equi
28、librated with water according to the isotopic exchange reaction 1: The 18 O/ 16 O isotopic ratios are determined by mass spectrometry by measuring the ratio of the intensities of ions having a mass of46 ( 12 C 16 O 18 O) to those with a mass of44 ( 12 C 16 O 2 ). 5 Reagents 5.1 Carbon dioxide of ana
29、lytical grade 5.2 SMOW and SLAP reference waters (obtainable from the International Atomic Energy Agency (IAEA) 1) ), 2. 6 Apparatus Usual laboratory apparatus and, in particular, the following: 6.1 Isotope ratio mass spectrometer, with the ability to determine 18 O content of CO 2gas natural abunda
30、nce with an internal precision of0,05 or better (expressed in relative d value (see8). The internal precision is here defined as the difference between two measurements of the same CO 2sample. This instrument should comprise: either a triple collector capable of simultaneous collections of the ions
31、with the respective masses of44,45 and46, or a double collector capable of simultaneous collection of ions with respective masses of44 and46; an inlet system capable of introducing carbon dioxide into the mass spectrometer after equilibration with both sample and reference liquids. 6.2 Sample bottle
32、s, which can be adequately sealed under vacuum and having identical sample volumes of at least10ml, and not more than30ml (water sample size of2ml and5ml, respectively), preferably made of borosilicate glass. 6.3 Pumping system, capable of obtaining a vacuum of0,13Pa during the sample preparation. 6
33、.4 Thermostatically controlled water bath, capable of being maintained at 25C 0,5 C. 7 Procedure 7.1 Sample preparation Products shall not normally require any pre-treatment. 7.2 CO 2equilibration step Pour into one of the calibrated sample bottles at least2ml and not more than5ml of the raw fruit j
34、uice (not centrifuged or filtered), depending on the size of sample bottles(6.2), then chill to 80C. ( 18 O/ 16 O) Isotope ratio of oxygen18 to oxygen16 for a considered sample; d 18 O Oxygen18 ( 18 O) content expressed in parts per thousand (); SMOW Standard Mean Ocean Water; SLAP Standard Light An
35、tartic Precipitation; GISP Greenland Ice Sheet Precipitation. (1) 1) International Atomic Energy Agency P.O. Box100 A -1400 Wien AUSTRIAENV 12141:1996 4 BSI 12-1998 Evacuate the air contained in the sample bottle under vacuum using the pump unit(6.3). Then introduce into the sample bottle the carbon
36、 dioxide(5.1) at a pressure of approximately80000Pa. Hermetically close the sample bottle and then place it in the thermostatically controlled water bath(6.4). The isotopic equilibrium is reached overnight (approximately 15h), but this period can be shortened to6h by shaking the samples. After equil
37、ibration, introduce the carbon dioxide contained in the sample bottle into the mass spectrometer(6.1) through a cryogenic trap maintained at 80C or a chemical trap capable of removing water vapour without isotopic fractionation of the carbon dioxide. 7.3 Determination Using the mass spectrometer(6.1
38、), measure the relative difference d in parts per thousand () between the ratio of the intensities of the ions having a mass of46 ( 12 C 16 O 18 O) to those with a mass of44 ( 12 C 16 O 2 ) obtained on the carbon dioxide equilibrated with the sample (I 46 /I 44 ) sampleand the reference carbon dioxi
39、de(5.1) (I 46 /I 44 ) reference ) using the following equation: 7.4 Calibration Carry out the same determination under the same conditions (quantity of water, of carbon dioxide, temperature) on standard SMOW and SLAP reference waters(5.2), and then measure d SMOW and d SLAP. 8 Calculation The same c
40、arbon dioxide gas used to equilibrate the samples, SLAP and SMOW reference waters is also used as the reference gas in the mass spectrometer, it follows that all the corrections than can be applied cancel themselves out from the equation and the oxygen18 ( 18 O) content of the sample with respect to
41、 the SMOW reference water is: The accepted value for the SLAP reference water is d 18 O = 55,5 SMOW 2. 9 Precision Details of the interlaboratory test on precision of the method are summarized in annex B. The values derived from the interlaboratory test may not be applicable to analyte concentration
42、 ranges and matrices other than given in annex B. 9.1 Repeatability The absolute difference between two single test results found on identical test material by one operator using the same apparatus within the shortest feasible time interval will exceed the repeatability limit r in not more than 5 %
43、of the cases. The values are: Orange juice r = 0,22 ; Apple juice r = 0,45 ; GISP 2)water r = 0,23 . 9.2 Reproducibility The absolute differences between two single test results on identical test material reported by two laboratories will exceed the reproducibility limit R in not more than5% of the
44、cases. The values are: Orange juice R =0,33 ; Apple juice R =0,58 ; GISP 2)water R =0,34 . 10 Test report The test report shall contain the following data: all information necessary for the identification of the sample (kind of sample, origin of sample, designation); a reference to this European Sta
45、ndard the date and type of sampling procedure (if known); the date of receipt; the date of test the test results and units in which they have been expressed; whether the repeatability of the method has been verified; any particular points observed in the course of the test; any operations not specif
46、ied in the method or regarded as optional, which might have affected the results. (2) (3) d sample I 46 /I 44 () sample I 46 /I 44 () reference -1 1 000 = d 18 O d sample d SMOW d SMOW d SLAP -55.5 = 2) GISP is a secondary international IAEA standardENV 12141:1996 BSI 12-1998 5 Annex A (informative)
47、 Bibliography 1 Variation of 18 O content of waters from natural sources. Epstein S, Mayeda T., Geoch. Cosmochim. Acta4, 213-244, 1953 2 Standards for stable isotope measurements in natural compounds. R. Gonfiantini, Nature 271, 534-536, 1978 Annex B (informative) Statistical results of the interlab
48、oratory test In accordance with ISO5725:1986, the following parameters have been defined in an interlaboratory test. (For literature pertaining to the method see annex A). The test was conducted by the Working Group1 “Isotope” of the CEN/TC174. Table B.1 Sample types: Year of the interlaboratory tes
49、t 1993 Number of laboratories 15 Number of samples 3 Sample A B C Number of laboratories retained after eliminating outliers 15 15 15 Number of outliers (laboratories) 0 0 0 Number of accepted results 45 45 42 Mean value () 2,52 3,48 24,72 Repeatability standard deviation (s r ) () 0,08 0,16 0,08 Repeatability relative standard deviation (RSD r ) () 3,17 4,60 0,32 Repeatabil
copyright@ 2008-2019 麦多课文库（www.mydoc123.com）网站版权所有
备案/许可证编号：苏ICP备17064731号-1