BS EN 1136-1995 Method for determination of phosphorus content of fruit and vegetable juices spectrometric method《果汁和蔬菜汁磷含量的测定方法 光谱法》.pdf

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1、BRITISH STANDARD BSEN 1136:1995 Method for Determination of phosphorus content of fruit and vegetable juices: Spectrometric method The European Standard EN1136:1994 has the status of a BritishStandard UDC 663.81/.82:620.1:543.42:661.632BSEN1136:1995 This BritishStandard, having been prepared under t

2、he directionof the Consumer Products and Services Sector Board, was published under the authority of the Standards Boardand comes into effect on 15January1995 BSI 12-1999 The following BSI references relate to the work on this standard: Committee reference AW/21 Draft for comment90/51495 DC ISBN 0 5

3、80 23165 8 Cooperating organizations The European Committee for Standardization (CEN), under whose supervision this European Standard was prepared, comprises the national standards organizations of the following countries: Austria Oesterreichisches Normungsinstitut Belgium Institut belge de normalis

4、ation Denmark Dansk Standardiseringsraad Finland Suomen Standardisoimisliito, r.y. France Association franaise de normalisation Germany Deutsches Institut fr Normung e.V. Greece Hellenic Organization for Standardization Iceland Technological Institute of Iceland Ireland National Standards Authority

5、of Ireland Italy Ente Nazionale Italiano di Unificazione Luxembourg Inspection du Travail et des Mines Netherlands Nederlands Normalisatie-instituut Norway Norges Standardiseringsforbund Portugal Instituto Portugus da Qualidade Spain Asociacin Espaola de Normalizacin y Certificacin Sweden Standardis

6、eringskommissionen i Sverige Switzerland Association suisse de normalisation UnitedKingdom British Standards Institution Amendments issued since publication Amd. No. Date CommentsBSEN1136:1995 BSI 12-1999 i Contents Page Cooperating organizations Inside front cover National foreword ii Foreword 2 1

7、Scope 3 2 Normative references 3 3 Symbols 3 4 Principle 3 5 Reagents 3 6 Apparatus 3 7 Procedure 3 8 Calculation 4 9 Precision 4 10 Test report 4 Annex A (informative) Bibliography 5 Annex B (informative) Statistical results of the inter-laboratory test 5 National annex NA (informative) Committees

8、responsible Inside back cover National annex NB (informative) Cross-references Inside back cover Table B.1 5BSEN1136:1995 ii BSI 12-1999 National foreword This British Standard has been prepared under the direction of the Consumer Products and Services Sector Board and is the English language versio

9、n of EN1136:1994 Fruit and vegetable juices Determination of phosphorus content spectrometric method, published by the European Committee for Standardization (CEN). EN1136 was produced as a result of international discussions in which the UnitedKingdom took an active part. A British Standard does no

10、t purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. 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 f

11、ront cover, pagesi andii, theEN title page, pages2 to6, 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 the inside front cover.EUROPEAN STANDARD NORME EUROPENNE EUROP

12、ISCHE NORM EN 1136 October 1994 UDC 663.81/.82:620.1:543.42:661.632 Descriptors: Food products, beverages, fruit and vegetable juices, chemical analysis, determination of content, phosphorus, spectrophotometric analysis English version Fruit and vegetable juices Determination of phosphorus content S

13、pectrometric method Jus de fruits et de lgumes Dtermination dela teneur en phosphore Mthode spectromtrique Frcht- und Gmusesfte Bestimmung des Phosphorgehaltes Spektralphotometrisches Verfahren This European Standard was approved by CEN on1994-09-29. CEN members are bound to comply with the CEN/CENE

14、LEC Internal 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 C

15、EN member. 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

16、members are the national standards bodies of Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and UnitedKingdom. CEN European Committee for Standardization Comit Europen de Normalisation Europi

17、sches Komitee fr Normung Central Secretariat: rue de Stassart 36, B-1050 Brussels 1994 Copyright reserved to CEN members Ref. No. EN 1136:1994 EEN1136:1994 BSI 12-1999 2 Foreword This European Standard has been prepared by the Technical Committee CEN/TC174, Fruit and vegetable juices Methods of anal

18、ysis, 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 April1995, and conflicting national standards shall be withdrawn at the latest by April1995. Annexe

19、s designated “informative” are given only for information. In this standard Annex A and Annex B are informative. According to the CEN/CENELEC Internal Regulations, the following countries are bound to implement this European Standard: Austria, Belgium, Denmark, Finland, France, Germany, Greece, Icel

20、and, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and UnitedKingdom.EN1136:1994 BSI 12-1999 3 1 Scope This European standard specifies a method for the determination of the phosphorus content of fruit and vegetable juices and related products. 2 Normative ref

21、erences This European Standard 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 dated references, subsequent amendments to or revisions of any of t

22、hese 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 1135:1994, Fruit and vegetable juices Determination of ash. ISO 5725:1986, Precision of test methods Determina

23、tion of repeatability and reproducibility for a standard test method by inter-laboratory test. ISO 3696:1987, Water for analytical laboratory use Specification and test methods. 3 Symbols For the purpose of this standard, the following symbols apply: c Substance concentration; Mass concentration. 4

24、Principle Phosphate and molybdate react in acid solution to form a phosphomolybdic complex. In a mixture of molybdic and phosphomolybdic acids, only the molybdenum in the form of phosphomolybdate is reduced to molybdenum-blue, by suitable reducing agents (ascorbic acid). The absorbance of the molybd

25、enum-blue, which is directly proportional to the phosphate content, is measured spectrometrically. Phosphate (PO 4 ) 3is expressed as phosphorous (P). 5 Reagents 5.1 General. Use only reagents of recognized analytical grade and only water of at least grade2 according to ISO3696:1987. 5.2 Hydrochlori

26、c acid, c(HCl)=2mol/l. 5.3 Sulfuric acid, c(H 2 SO 4 )=1 mol/l. 5.4 L-Ascorbic acid, (Vitamin C) c(C 6 H 8 O 6 )=0,02mol/l=0,353g/100ml. This solution shall be freshly prepared. 5.5 Ammonium molybdate solution. Dissolve approximately2g ammonium molybdate (NH 4 ) 6 Mo 7 O 24 .4H 2 O) in about60ml war

27、m water(60 C). Cool to about20 C and transfer to a100ml graduated flask and dilute to100ml with water. 5.6 Standard phosphorus solution, (P)=1,0g/l. Dissolve11,5627g Na 2 HPO 4 .12H 2 O in water and dilute to1l with water. 6 Apparatus Usual laboratory apparatus and, in particular, the following: 6.1

28、 Platinum dish, approximately80mm diameter. 6.2 Muffle furnace, capable of maintaining a temperature of525 C 25 C. 6.3 Water bath 6.4 Spectrometer, capable of measuring at720nm. 6.5 Cuvettes, of10mm optical path length, and which have no significant absorption at720nm. 7 Procedure 7.1 Preparation of

29、 the test sample Normally products shall not be pretreated 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. I

30、n this case, the relative density shall 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 high viscosity and/or very high content of cells (for example pulp), determination on

31、the basis of a weighed test sample is the usual procedure. 7.2 Test procedure 7.2.1 Preparation of the standard curve solutions Prepare the standard curve solutions so that concentration of the final test solutions measured spectometrically (see7.2.3) shall contain phosphorus at concentrations withi

32、n the range of0,1mg/l to1,5mg/l of P using suitable dilutions of the standard phosphorus solution(5.6). The solutions are treated as described in section7.2.3. 7.2.2 Preparation of the test sample for spectrometric analysis Dissolve the white ash from25ml of test sample which has been ashed accordin

33、g to EN1135 in2ml to3ml hydrochloric acid(5.2) and transfer the solution to a50ml volumetric flask and make up to the mark.EN1136:1994 4 BSI 12-1999 7.2.3 Spectrometric analysis Pipette a suitable volume (recommended volumes: for grape and orange juices2ml; for apple juice5ml) of test sample prepare

34、d as in clause7.2.2, or standard curve solution, into a100ml volumetric flask. Dilute with water to about50ml then add20ml sulfuric acid(5.3), 4ml ammonium molybdate solution(5.5) and2ml L-ascorbic acid solution(5.4). In some samples of vegetable juices the high content of nitrate present interferes

35、 with the reduction of the phosphomolybdate complex and so the amount of ascorbic acid solution(5.4;2ml) may be insufficient. In such cases use a higher concentration of ascorbic acid (e.g.10g/l). Place the flask (not stoppered) in a boiling water-bath for15minutes, then cool to room temperature and

36、 make the volume up to100ml. Measure the absorbance of the solution in the spectrometer at720nm against water. The absorbance of this solution remains constant for up to3h and the Beer-Lambert law is obeyed for concentrations between0,1mg/l and1,5mg/l of P. 8 Calculation Plot the curve of absorbance

37、 against P concentration for the standard solutions. Calculate the phosphorous content, expressed as milligrams of phosphorous per litre, from the following expression: Take into account the dilution factor and the relation of the value to mass or volume. If a concentrated product has been diluted t

38、o single strength, report the relative density of the single strength sample. Express the phosphorus content as milligrams of phosphorus per litre, to one decimal place. NOTEThe phosphate content may be calculated from the phosphorous content (P) by multiplying (P) by the factor3,066. 9 Precision De

39、tails of the inter-laboratory test on precision of the method are summarized in Annex B. The values derived form the inter-laboratory test may not be applicable to analyte concentration ranges and matrices other than given in Annex B. 9.1 Repeatability The absolute difference between two single test

40、 results found on identical test material by one operator using the same apparatus within the shortest feasible time interval will exceed the repeatability value r in not more than5% of the cases. The values are: clear juices: r=4mg/l cloudy juices: r=8mg/l 9.2 Reproducibility The absolute differenc

41、e between two single test results on identical test material reported by two laboratories will exceed the reproducibility value R in not more than5% of the cases. The volumes are: clear juices: R=10mg/l cloudy juices: R=21mg/l. 10 Test report The test report shall contain the following data: all inf

42、ormation 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 (ifpossible); the date of receipt; the date of test; the test results and units in which they have been expressed; w

43、hether the repeatability 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. where: a is the phosphorous content in milligrams perlitre of the final solution prepared a

44、s in(7.2.3), corresponding to the absorbance ofthe same final solution as measured in(7.2.3) and read from the standard curve; V is the volume of test sample used, in millilitres. P() 200 a V - =EN1136:1994 BSI 12-1999 5 Annex A (informative) Bibliography 1 Determination of phosphate: No50,1983. In:

45、 AnalysesCollection/International Federation of Fruit Juice Producers. Loose-leaf edition, as of1989. Zug: Swiss Fruit Union. 2 Untersuchung von Lebensmitteln: Bestimmung von Phosphat in Fruchtsften: L31.00-6,1980-05 FoodAnalysis: Determination of phosphate in fruit juices: L31.00-6,1980-05 -In: Amt

46、liche Sammlung von Untersuchungsverfahren nach 35LMBG: Verfahren zur Probenahme und Untertsuchung von Lebensmitteln, Tabakereugnissen, kosmetischen Mitteln und Bedarfsgegnstnden/Bundesgesundheitsamt In: Collection of official methods under article 35 of the German Federal Foods Act: Methods of sampl

47、ingand analysis of foods, tobacco products, cosmetics and commodity goods/Federal Health Office -Loseblattausgabe, Stand31.12.1991, Bd.l. Loose-leaf edition, as of1991-12-31, Vol.1. -Berlin, Kln: Beuth Verlag GmbH. Annex B (informative) Statistical results of the inter-laboratory test In accordance

48、with ISO5725:1986, the following parameters have been defined in an inter-laboratory test. (For literature pertaining to the method see Annex A). The test was conducted by the Max von Pettenkofer Institute of the Federal Health Office, Food and Chemistry Department, Berlin, BRD. Table B.1 Year of in

49、ter-laboratory test 1977 number of laboratories 13 number of samples 4 Sample A B C D Number of laboratories retained after eliminating outliers Number of outliers (Laboratories) Number of accepted results 12 1 61 13 68 11 2 58 11 2 56 Mean value(mg/l) 67 79 122 179 Repeatability standard deviation (s r )(mg/l) Repeatability relative standard deviation (RSD r )% 1,13 1,69 1,23 1,56 1,39 1,14 2,99 1,67 Repeatability limit (r)(mg/l) 3,2 3,2 3,9 8,4 Reproduci