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1、| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | BRITISH STANDARD BS EN 12133 : 1998 The Eu
2、ropean Standard EN 12133 : 1997 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 chloride content Potentiometric titration method Licensed Copy: sheffieldun sheffieldun, na, Sat Oct 2
3、8 08:46:17 GMT+00:00 2006, Uncontrolled Copy, (c) BSI This British Standard, having been prepared 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 February 1998 BSI 1998 ISBN 0 580 28968 0 BS
4、EN 12133 : 1998 Amendments issued since publication Amd. No.DateText affected National foreword This British Standard is the English language version of EN 12133. The UK participation in its preparation was entrusted to Technical Committee AW/21, Fruit and vegetable juices, which has the responsibil
5、ity to: aid enquirers to understand the text; present to the responsible European committee any enquiries on the interpretation, or proposals for change, and keep the UK interests informed; monitor related international and European developments and promulgate them in the UK. A list of organizations
6、 represented on this committee can be obtained on request to its secretary. Cross-references The British Standards which implement international or European publications referred to in this document may be found in the BSI Standards Catalogue under the section entitled International Standards Corres
7、pondence Index, or by using the Find facility of the BSI Standards Electronic Catalogue. 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, the EN title page, pages 2 to 6, an in
8、side back cover and a back cover. Licensed Copy: sheffieldun sheffieldun, na, Sat Oct 28 08:46:17 GMT+00:00 2006, Uncontrolled Copy, (c) BSI CEN European Committee for Standardization Comite Europe en de Normalisation Europa isches Komitee fu r Normung Central Secretariat: rue de Stassart 36, B-1050
9、 Brussels 1997 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN 12133 : 1997 E EUROPEAN STANDARDEN 12133 NORME EUROPE ENNE EUROPA ISCHE NORM September 1997 ICS 67.160.20 Descriptors: Fruit and vegetables juices, chemical analysis, d
10、etermination of content, chlorides, potentiometric methods, procedures English version Fruit and vegetable juices Determination of chloride content Potentiometric titration method Jus de fruits et de le gumes Dosage des chlorures Me thode de titrage potentiome trique Frucht- und Gemu sesa fte Bestim
11、mung des Chloridgehaltes Potentiometrisches Titrationsverfahren This European Standard was approved by CEN on 6 September 1997. CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard
12、 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 member. This European Standard exists in three official versions (English, French, German). A version in any other langu
13、age 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 are the national standards bodies of Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece, I
14、celand, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom. Licensed Copy: sheffieldun sheffieldun, na, Sat Oct 28 08:46:17 GMT+00:00 2006, Uncontrolled Copy, (c) BSI Page 2 EN 12133 : 1997 BSI 1998 Foreword This European Standard has been prepar
15、ed by Technical Committee CEN/TC 174, Fruit and vegetable juices Methods of analysis, the Secretariat of which 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 1998, and con
16、flicting national standards shall be withdrawn at the latest by March 1998. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Czech Republic, Denmark, Finland, France, Ge
17、rmany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and the United Kingdom. Contents Page Foreword2 1Scope3 2Normative references3 3Symbols3 4Principle3 5Reagents3 6Apparatus3 7Procedure3 8Calculation4 9Precision5 10Test report5 Annexes A(inf
18、ormative) Bibliography6 B(informative) Statistical results of the inter-laboratory test6 Licensed Copy: sheffieldun sheffieldun, na, Sat Oct 28 08:46:17 GMT+00:00 2006, Uncontrolled Copy, (c) BSI Page 3 EN 12133 : 1997 BSI 1998 1 Scope This European Standard specifies a potentiometric titration meth
19、od for the determination of the chloride content of fruit and vegetable juices and related products. 2 Normative references This European Standard incorporates by dated or undated reference, provisions from other publications. These normative references are cited at the appropriate places in the tex
20、t and the publications are listed hereafter. For dated references, subsequent amendments to or revisions 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 applie
21、s. EN ISO 3696 : 1995Water for analytical laboratory use Specification and test methods (ISO 3696 : 1987) ISO 5725 : 1986Precision of test methods Determination of repeatability and reproducibility for a standard test method by inter- laboratory tests 3 Symbols For the purposes of this European Stan
22、dard, the following symbols apply: csubstance concentration rmass concentration vmass fraction dspecific gravity nthe volume in millilitres of the silver nitrate standard solution used to titrate the chloride content of the fruit juice sample using the end potential method Vvolume of standard soluti
23、on at the equivalence point V9volume of standard solution added before the potential rise DViconstant volume for addition of the standard solution, (e.g. 0,2 ml) DEfirst potential difference DDEsecond potential difference DDE1second potential difference before the biggest potential rise DDE2second p
24、otential difference after the biggest potential rise 4 Principle The chloride content is determined by potentiometric titration using a silver/silver chloride electrode. 5 Reagents 5.1 General Use only reagents of recognized analytical grade and only water in accordance with at least grade 2 of EN I
25、SO 3696 : 1995. 5.2 Potassium chloride The potassium chloride shall contain no more than 0,005 % (m/m) bromide and shall be dried for three to four days in a desiccator before use. 5.3 Nitric acid, v(HNO3) $ 65 g/100 g, d $ 1,4. 5.4 Potassium chloride solution, r(KCl) = 1,8636 g/l. Dissolve 1,8636 g
26、 of potassium chloride (5.2) in 1 l of water (5.1). 1 ml of this solution contains 0,886 mg of chloride. 5.5 Silver nitrate standard solution, c(AgNO3) = 0,025 mol/l. 1 ml of this solution reacts with 0,886 mg of chloride. 6 Apparatus Usual laboratory apparatus and, in particular, the following: 6.1
27、 pH-millivoltmeter, readable to at least 2 mV. 6.2 Magnetic stirrer. 6.3 Ag/AgCl electrode, with saturated potassium nitrate solution as electrolyte. 6.4 Micro-burette, readable to at least 0,01 ml. 7 Procedure 7.1 Preparation of the test sample Normally products shall not be pre-treated, however di
28、lution may be necessary and their analysis by this method shall be on a volumetric basis, results being expressed per litre of sample. The analysis of concentrated products may also be carried out on a volumetric basis, after dilution to a known relative density. In this case, the relative density s
29、hall be indicated. Based on a weighed sample and taking the dilution factor for analysis into account, the results may also be expressed per kilogram of product. In products with a high viscosity and/or a very high content of cells (for example pulp), a determination on the basis of a weighed test s
30、ample is the usual procedure. Mix cloudy samples well before dilution. Licensed Copy: sheffieldun sheffieldun, na, Sat Oct 28 08:46:17 GMT+00:00 2006, Uncontrolled Copy, (c) BSI Page 4 EN 12133 : 1997 BSI 1998 7.2 Test procedure Following the manufacturers instructions for the apparatus used, either
31、 titrate to the end potential or plot the potential curve. 7.2.1 Titration to the end potential Pipette 5,0 ml of standard chloride solution (5.4) into a 150 ml beaker. Dilute to approximately 100 ml with distilled water (5.1) and add 1,0 ml of nitric acid (5.3). Dip the electrode (6.3) into the sol
32、ution, and add silver nitrate solution (5.5) from the micro-burette (6.4) while stirring slowly using the magnetic stirrer (6.2). Titrate a total of 4,00 ml in steps of 1,00 ml, recording the potential in millivolts at each step on the pH-millivoltmeter (6.1). Then titrate a further 2,00 ml, in step
33、s of 0,2 ml. Finally, titrate up to a total of 10,00 ml in 1,00 ml steps. After each addition, wait about 30 s before reading the potential in millivolts. Plot the values obtained against the volume (in millilitres) of standard solution added. Hence estimate the end potential from the inflection poi
34、nt on the curve. Pipette 5,0 ml of standard chloride solution (5.4) into a 150 ml beaker. Add 95 ml of water (5.1), followed by 1,0 ml of nitric acid (5.3). After inserting the electrode, titrate the solution to the equivalence potential obtained previously. This estimation should be repeated until
35、a reproducible figure is obtained. This figure then serves for all the chloride estimations in each particular batch of samples. Pipette 50,0 ml of a suitably diluted sample into a 150 ml beaker. Add 50 ml of distilled water followed by 1,0 ml of nitric acid, and titrate as above. 7.2.2 Determinatio
36、n of potential curve For particularly accurate determinations it is possible to obtain the complete titration curve of the test sample against silver nitrate standard solution. The equivalence point can then be obtained graphically, or, for the highest accuracy, by calculation. Pipette 50 ml of the
37、suitably diluted sample into a 150 ml beaker with 50 ml of distilled water (5.1) and 1 ml of nitric acid (5.3). Titrate against the silver nitrate standard solution in 0,5 ml steps and record the corresponding potential at each step. Use this initial titration to give the rough titration volume. Rep
38、eat the estimation under the same conditions. Begin in 0,5 ml steps and reduce these to 0,2 ml steps once within 1,5 ml to 2,0 ml of the expected endpoint. Continue similarly after the endpoint and then raise the steps to 0,5 ml in a symmetrical fashion. 8 Calculation 8.1 Calculation for the end pot
39、ential technique If n ml of silver nitrate solution were used, the chloride content rCl2, in milligrams per litre, is calculated from the following equation: rCl2 = n 17,72(1) Take into account any dilution factor and the relationship of the value to mass or volume in the final calculation. If a con
40、centrated product has been diluted to single strength, report the relative density of the single strength sample. Report the chloride content for fruit juice in milligrams per litre to one decimal place, and for vegetable juice in grams per litre to one decimal place. 8.2 Calculation for the potenti
41、al curve technique The volume of standard solution at the equivalence point is calculated from the following expression: V = V9 + DVi(2) DDE1 DDE1+ DDE2 The chloride content rCl2, in milligrams per litre, is calculated from the following expression: rCl2 = V 17,72(3) Take into account any dilution f
42、actor and the relationship of the value to mass or volume in the final calculation. If a concentrated product has been diluted to single strength, report the relative density of the single strength sample. Report the chloride content for fruit juice in milligrams per litre to one decimal place, and
43、for vegetable juice in grams per litre to one decimal place. Table 1. Example c (AgNO3) = 0,025 mol/l Potential1st difference DE 2nd difference DDE mlmVmVmV 0,02044 0,22084 0,42126 0,62186 0,82246 1,02308 1,223812 1,425022 1,62724422 1,83163410 2,035026 2,237620 2,4396 In this example, the endpoint
44、of the titration is between 1,6 ml and 1,8 ml, where the largest potential rise takes place (DE = 44 mV). The volumes used for calculation of this point are as follows: V = 1,6 + 0,2 = 1,74 ml(4) 22 22 + 10 Licensed Copy: sheffieldun sheffieldun, na, Sat Oct 28 08:46:17 GMT+00:00 2006, Uncontrolled
45、Copy, (c) BSI Page 5 EN 12133 : 1997 BSI 1998 9 Precision Details of the inter-laboratory test on the precision of the method are summarized in annex B. The values derived from the inter-laboratory test may not be applicable to analyte concentration ranges and matrices other than given in annex B. 9
46、.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 cases. The values are: orange juice: r = 1,2
47、 mg/l; tomato juice: r = 0,1 g/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: orange juice: R = 6,6 mg/l; tomato juice: R
48、 = 0,2 g/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 procedure (if known); the date of receipt;
49、 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 optional, which might have affected the results. Licensed Copy: sheffieldun sheffieldun, na, Sat Oct 28 08:46:17 GMT+00:00 2006, Uncontrolled Copy, (c) BSI Page 6 EN 12133 : 1997 BSI 1998 Annex A (informative) Bibliography Hadorn, H. Chlorhaltige Extraktionsmittel-R