1、| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | BRITISH STANDARD BS EN 12144 : 1997 The Eu
2、ropean Standard EN 12144 : 1996 has the status of a British Standard ICS 67.160.20 NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW Fruit and vegetable juices Determination of total alkalinity of ash Titrimetric methodBS EN 12144 : 1997 This British Standard, having been prepar
3、ed under the direction of the Consumer Products and Services Sector Board, was published under the authority of the Standards Board and comes into effect on 15 May 1997 BSI 1997 The following BSI references relate to the work on this standard: Committee reference AW/21 Draft for comment 89/54810 DC
4、ISBN 0 580 27056 4 Amendments issued since publication Amd. No. Date Text affected Committees responsible for this British Standard The preparation of this British Standard was entrusted to Technical Committee AW/21, Fruit and vegetable juices, upon which the following bodies were represented: Briti
5、sh Fruit Juice Importers Association British Retail Consortium British Soft Drinks Association Limited Campden and Chorleywood Food Research Association Laboratory of the Government Chemist Leatherhead Food Research Association Ministry of Agriculture, Fisheries and Food Royal Society of ChemistryBS
6、 EN 12144 : 1997 BSI 1997 i Contents Page Committees responsible Inside front cover National foreword ii Foreword 2 Text of EN 12144 3ii BSI 1997 BS EN 12144 : 1997 National foreword This British Standard has been prepared by Technical Committee AW/21, and is the English language version of EN 12144
7、 : 1996 Fruit and vegetable juices Determination of total alkalinity of ash Titrimetric method, published by the European Committee for Standardization (CEN). EN 12144 was produced as a result of international discussions in which the United Kingdom took an active part. Cross-references Publication
8、referred to Corresponding British Standard EN ISO 3696 : 1995 BS EN ISO 3696 : 1995 Specification for water for laboratory use EN 1135 : 1994 BS EN 1135 : 1995 Method for determination of ash of fruit and vegetable juices ISO 5725 : 1986, to which informative reference is made in the text, has been
9、superseded by ISO 5725-1 : 1994, ISO 5725-2 : 1994, ISO 5725-3 : 1994, ISO 5725-4 : 1994 and ISO 5725-6 : 1994 which are identical with BS ISO 5725 Accuracy (trueness and precision) of measurement methods and results, BS ISO 5725-1 : 1994 General principles and definitions, BS ISO 5725-2 : 1994 Basi
10、c methods for the determination of repeatability and reproducibility of a standard measurement method, BS ISO 5725-3 : 1994 Intermediate measures of the precision of a standard measurement method, BS ISO 5725-4 : 1994 Basic methods for the determination of the trueness of a standard measurement meth
11、od, and BS ISO 5725-6 : 1994 Use in practice of accuracy values. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, the EN title page, pages 2 to 6, an inside bac
12、k cover and a back cover.CEN European Committee for Standardization Comite Europe en de Normalisation Europa isches Komitee fu r Normung Central Secretariat: rue de Stassart 36, B-1050 Brussels 1996 Copyright reserved to CEN members Ref. No. EN 12144 : 1996 E EUROPEAN STANDARD EN 12144 NORME EUROPE
13、ENNE EUROPA ISCHE NORM September 1996 ICS 67.160.20 Descriptors: Food products, beverages, fruit and vegetable juices, chemical analysis, ash determination, alkalinity, volumetric analysis English version Fruit and vegetable juices Determination of total alkalinity of ash Titrimetric method Jus de f
14、ruits et de le gumes De termination de lalcalinite totale des cendres Me thode titrime trique Frucht- und Gemu sesa fte Bestimmung der Aschen-Gesamtalkalita t Titrimetrisches Verfahren This European Standard was approved by CEN on 1996-05-09. CEN members are bound to comply with the CEN/CENELEC Inte
15、rnal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the Central Secretariat or to any CEN membe
16、r. This European Standard exists in three official versions (English, French, German). A version in any other language made by translation under the responsibility of a CEN member into its own language and notified to the Central Secretariat has the same status as the official versions. CEN members
17、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.Page 2 EN 12144 : 1996 BSI 1997 Foreword This European Standard has been prepared by the
18、 Technical Committee CEN/TC 174, Fruit and vegetable juices Methods of analysis, of which the Secretariat is held by AFNOR. This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by March 1997, and conflict
19、ing national standards shall be withdrawn at the latest by March 1997. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Denmark, Finland, France, Germany, Greece, Icelan
20、d, 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 Definition and symbol 3 4 Principle 3 5 Reagents 3 6 Apparatus 3 7 Procedure 3 8 Calculation 3 9 Precision 4 10 Test report 4
21、 A (informative) Bibliography 5 B (informative) Statistical results of the interlaboratory test 5Page 3 EN 12144 : 1996 BSI 1997 1 Scope This European Standard specifies a method for the titrimetric determination of the total alkalinity of ash in fruit and vegetable juices and related products. 2 No
22、rmative references This European Standard incorporates by dated or undated references, provisions from other publications. These normative references are cited at the appropriate places in the text and the publications are listed hereafter. For dated references, subsequent amendments to or revisions
23、 of any of these publications apply to this European Standard only when incorporated in it by amendment or revision. For undated references the latest edition of the publication referred to applies. EN ISO 3696 : 1995 Water for analytical laboratory use Specification and test methods ISO 5725 : 1986
24、 Precision of test methods Determination of repeatability and reproducibility for a standard test method by inter-laboratory tests EN 1135 : 1994 Fruit and vegetable juices Determination of ash 3 Definition and symbol 3.1 Definition For the purposes of this standard the following definition applies:
25、 total alkalinity of ash The alkalinity, expressed in millimoles of sodium hydroxide per litre, of the ash obtained using the method specified in this standard. 3.2 Symbol For the purposes of this standard the following symbol applies: c = substance concentration 4 Principle After determination of t
26、he ash content of the sample, according to EN 1135 : 1994, the ash is dissolved in an excess of sulfuric acid solution by heating. After cooling, the excess acid is back titrated with standard volumetric sodium hydroxide solution using a mixed indicator (methyl red/methylene blue). 5 Reagents 5.1 Ge
27、neral Use only reagents of recognized analytical grade and only water in accordance with at least grade 3 of ISO 3696 : 1987. 5.2 Sulfuric acid, standard volumetric solution, c(H 2 SO 4 ) = 0,05 mol/l. 5.3 Sodium hydroxide, standard volumetric solution, c(NaOH) = 0,1 mol/l. 5.4 Methyl red/methylene
28、blue indicator solution. Dissolve 100 mg of methyl red and 50 mg of methylene blue in 100 ml of mixture from 50 ml ethanol and 50 ml water. 6 Apparatus Usual laboratory apparatus and, in particular, the following: 6.1 Platinum dish with watch glass. 6.2 Waterbath. 6.3 Burette, of capacity 10 ml, gra
29、duated in 0,02 ml divisions. 7 Procedure 7.1 Preparation of the test sample Prepare ash from 25 ml juice as described in method EN 1135 : 1994. 7.2 Test procedure Moisten the ash (7.1) with a little water. Add a measured excess of the standard volumetric sulfuric acid solution (5.2). Cover the plati
30、num dish with the watch glass (6.1) and heat for 15 min on the waterbath (6.2), taking care to avoid evaporation to dryness. Transfer the contents of the dish by repeated careful rinsing of the platinum dish and the watch glass with water into a 150 ml conical flask. Cool the flask and contents, add
31、 a few drops of the indicator solution (5.4) and titrate with the standard volumetric sodium hydroxide solution (5.3), previously standardized against the same indicator. NOTE. The indicator colour change is from violet/red to colourless. 8 Calculation The total alkalinity of the ash, c, in millimol
32、es of sodium hydroxide per litre is given by the formula: c =43(V 1 2V 2 ) where V 1 is the volume, in millilitres, of sulfuric acid standard volumetric solution (5.2) required; V 2 is the volume, in millilitres, of sodium hydroxide solution (5.3) used. Report the total alkalinity of the ash in mill
33、imoles of sodium hydroxide per litre, to the nearest 0,1 mmol/l.Page 4 EN 12144 : 1996 BSI 1997 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 ranges
34、 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 % of the
35、cases. The value is: r = 1,3 mmol NaOH/l. 9.2 Reproducibility The absolute difference between two single test results on identical test material reported by two laboratories will exceed the reproducibility limit R in not more than 5 % of the cases. The values are: samples other than orange juice R =
36、 1,8 mmol NaOH/l; orange juice R = 4,2 mmol NaOH/l. 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 Standard; the date and type of sampling pr
37、ocedure (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 specified in the method or regarded as opti
38、onal, which might have affected the results.Page 5 EN 12144 : 1996 BSI 1997 Table B.1. Sample A B C D Number of laboratories retained after eliminating outliers 11 13 13 14 Number of outliers (laboratories) 311 Number of accepted results 56 66 65 70 Mean value (mmol NaOH/l) x 2 30,3 24,5 63,9 44,3 R
39、epeatability standard deviation (s r ) (mmol NaOH/l) 0,4721 0,2905 0,5140 0,4733 Repeatability relative standard deviation (RSD r ) (%) 1,56 1,19 0,8 1,07 Repeatability limit (r) (mmol NaOH/l) 1,32 0,81 1,44 1,33 Reproducibility standard deviation (s R ) (mmol NaOH/l) 0,8033 0,4513 1,5013 0,6958 Rep
40、roducibility relative standard deviation (RSD R ) (%) 2,65 1,84 2,35 1,57 Reproducibility limit (R) (mmol NaOH/l) 2,25 1,26 4,20 1,95 NOTE. Orange juice shows higher values for R, because of content and/or matrix effects. Annex A (informative) A.1 Bibliography 1 Determination of ash alkalinity. Meth
41、od No. 10 (1989) In: The collected analyses of the International Federation of Fruit Juice Producers. Loose-leaf edition of 1996. Zug: Swiss Fruit Union. Annex B (informative) B.1 Statistical results of the interlaboratory test In accordance with ISO 5725 : 1986, the following parameters have been d
42、efined in an inter-laboratory test. (For literature pertaining to the method see annex A.) The test was conduced by the Max von Pettenkofer Institute of the Federal Health Office, Food Chemistry Department, Berlin, BRD. Year of interlaboratory test 1977 Number of laboratories 14 Number of samples 4
43、Sample types: A apple juice; B blackcurrant nectar; C orange juice; D grapejuice, white.6 blank BSI 1997 BS EN 12144 : 1997 List of references See national foreword.BSI 389 Chiswick High Road London W4 4AL | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
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