EN ISO 10520-1998 en Native Starch - Determination of Starch Content - Ewers Polarimetric Method《天然淀粉 淀粉含量的测定 Ewers旋光计法 ISO 10520-1997》.pdf

1、- STD-BSI BS EN IS0 L0520-ENGL 1998 ZbZqbb7 0738222 980 BRITISH STANDARD Native starch - Determination of starch content - Ewers polarimetric method The European Standard EN IS0 105201998 has the status of a British Standard ICS 67.iao.20 3s EN IS0 10520:1998 NO COPYING WITHOUT BSI PERMISSION EXCEPT

2、 AS PERMITTED BY COPYRIGHT LAW STD-BSI BS EN IS0 10520-ENGL L798 1b2qbb 07i8213 817 m AmdNo. BS EN IS0 10620:1998 Date Text affected This British Standard, having been prepared under the direction of the Consumer Products and SeMces Sector Committee, was published under the authority of the Standard

3、s Committeee and comes into effect on 15 November 1998 O BSI 1998 ISBN O 080 30398 O National foreword This British Standard is the English language version of EN IS0 10520:1!398. It is identical with IS0 10520A997. This British Standard has been produced to fulfil BSIs obligation to publish ali app

4、roved European Standards but, because of the absence of interest in the UK in the subject concerned, there has been no UK participation in the preparation of EN 10520. Any queries relating to the EN should be directed to BSI quoting the reference AWI100. Cross-references Attention is ram to the fact

5、 that CEN and CENELEC standards normally include an annex which lists normative references to international publications with their corresponding European publications. The British Standards which implement intedonal or European publidions referred to in this document may be found in the BI Standard

6、s Catalogue under the section entitled “Intedonal Standards Correspondence Index“, or by using the “Fnd“ faciiity of the BSI Standards Electronic Catalogue. A British Standard does not purport to include all the necessary provisions of a contract Users of British Standards are responsible for their

7、correct application. Compliance with a British Standard does not of itself confer immunity from legai obligations. Summary of pages This document comprises a fiont cover, an inside front cover, the EN IS0 titie page, the EN IS0 foreword page, the IS0 titie page, page ii, page 1 to 8, the annex ZA pa

8、ge and a back cover. Amendments issued since publication STD.BSI RS EN IS0 10520-ENGL 1998 1b24bb7 0739211i 753 EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN IS0 10520 September 1998 ICs 67.180 Descriptors: see IS0 document English version Native starch - Determination of starch content - Ewe

9、rs polarimetric method (IS0 10520:1997) Amidons et Wules natifs - Dosage de lamidon - Mthode poiarimtrique de Em (IS0 10520:1997) Native Strke - Bestimmung des Stirkegehnltes - Pdarims Verfahren nach Ewm (Is0 105201997) TMs European Standard was approved by CEN on 10 August 1998. CEN members are bow

10、id to comply with the CENCENELEC internai Regulations wMch Stipulae the cmdiom foi gMng this Europe Standard the stahir of a nationel rrtandard without any efteration. Up-to-date lists and Mblbgmphid references concemlng such nationel smdards may be shake vigorously six times during the hour to ensu

11、re thorough mixing of the test sample with the ethanol. Dilute to 1 O0 ml with ethanol (4.3), homogenize and filter. 7.2.2 Pipette 50 ml of the filtrate (equivalent to 2,5 g of the test portion) into a volumetric flask (5.1). Add 2,l ml of the dilute hydrochloric acid (4.1) and shake vigorously. Fit

12、 a reflux condenser to the flask and immerse the flask in a boiling water bath. Remove the flask from the boiling water bath after 15 min f 5 s. Cool to 20 “C f 2 “C. 7.2.3 Clarify the solution using Carrez I and II solutions as in 7.1.4, 7.1.5 and then continue as in 7.1.6. 7.2.4 Measure the optica

13、l rotation (a,) of the solution as in 7.1.7. 3 EN IS0 10620:1998 Starchtype Rice starch 7.3 Determination of dry matter content Numerical value of a %o (degrees) + 185.9 Determine the moisture content of the test sample, WO, in accordance with the method given in IS0 1666. Then calculate the dry mat

14、ter content, w1, of the test sample using the following equation: w1= loo-wo Maize starch Wheat starch Barley starch Oat starch starch mixtures Other types of starch and 8 Expression of results Calculate the starch content of the dry matter content of the test sample, w, as a percentage by mass, usi

15、ng the following equation: + 184,6 + 182,7 + 181,5 + 181,3 + 184,o where is the numerical value of the total optical rotation measured in 7.1, in degrees; is the numerical value of the optical rotation of the ethanol-soluble substances measured in 7.2, in degrees; is the numerical value of the mass

16、of the test portion in 7.1 .l, in grams; is the numerical value of the mass of the test portion in 7.2.1, in grams; is the numerical value of the dry matter content of the test sample determined in 7.3, as a percentage by mass; is the numerical value of the specific optical rotation of pure starch m

17、easured at a wavelength of 589,3 nm, in degrees. (See table 1 .) al % m1 m2 W1 Up Table 1 1- Potato starch I + 185,7 I Round the result to one decimal place. 9 Precision The precision of the method was established by an interlaboratory test organized by ISOKC 9WG 1, Det81mintttion of starch content,

18、 in 1990 and carried out in accordance with 4 STD-BSI BS EN IS0 1052U-ENGL 1998 E Zb24bb9 0738222 82T E EN IS0 10620:1998 Starch type Maize Potato Wheat Waxy maize IS0 5725 l. In this test, 12 laboratories participated. Samples investigated included maize starch, potato starch and wheat starch. The

19、statistical results are summarized in annex A. Repeatability limit Reproducibility limit r% (m/m) R % (f?7/m) 22 498 190 797 2,o 395 184 42 9.1 Repeatability The absolute difference between two independent single test results, obtained using the same method on identical test material in the same lab

20、oratory by the same operator using the same equipment within a short interval of time, should not be greater than the repeatability limit shown in table 2 for the type of starches listed. 9.2 Reproducibility The absolute difference between two single test results, obtained using the same method on i

21、dentical test material in different test laboratories with different operators using different equipment, should not be greater than the reproducibility limit shown in table 2 for the type of starches listed. Table 2 10 Testreport The test report shall specify - the method used, - the test result(s)

22、 obtained, and - if the repeatability has been checked, the final quoted result obtained. It shall also mention all operating details not specified in this International Standard, or regarded as optional, together with details of any incidents which may have influenced the test result). The test rep

23、ort shall include all information necessary for the complete identification of the sample. 5 STD-BSI 8s EN IS0 10520-ENGL 1798 Lb2LibbS 0738223 7bb EN IS0 10620:1998 Annex A (informative) Ewers method - Collaborative study 1990 Collaborative study The calculated values for the reproducibility relati

24、ve standard deviation (RSDR) or reproducibility coefficient of variation, in relation to the concentration level, were comparable with those in the table quoted by Pocklington 141. An equation was derived empirically by Horwitz from examination of more than 3 o00 collaborative (method performance) s

25、tudies. RSDR = 2 (1 - 095 Ig C) where c is the concentration expressed as a decimal fraction. From this equation, when c = 1 , RSDR = 2 % It is recognized that, where values for RSDR are in the range between 1 and 4 at this concentration, the precision is acceptable for method performance between la

26、boratories. The relative standard deviation within laboratories (repeatability) RSD, is frequently between half and two-thirds of RSDR. In table A.l , values for RSDR range from 1,25 % to 3,24 %. 6 STD.BS1 BS EN IS0 10520-ENGL 1998 m Lb24bb7 0738224 bT2 m EN IS0 10520:1998 “r I 7 - STD-BSI BS EN IS0

27、 L0520-ENGL 1998 Lb29bbS 0738225 537 EN IS0 10620:1998 Annex B (informative) Bibliography l IS0 57251 986, Precision of test methods - Detemination of repeatability and reproducibility for a standard test method by inter-/aboratory tests (now withdrawn), was used to obtain the precision data. 2 IS0

28、5725-1 :1994, Accuracy (trueness and precision) of measurement methods and results - Part 1 : General principles and definitions 3 IS0 5725-2: 1994, Accuracy (trueness and precision) of measurement methods and results - Part 2 .- A basic method for the determination or repeatability and reproducibil

29、ify of a standard measurement method 4 International Union of Pure and Applied Chemistry, Harmonized protocols for the adoption of standardized analytical methods and for the presentation of their performance characteristics. J. Pure APPL them., 62, NO 1 , 1990, p.152. 8 STD-BSI BS EN IS0 L0520-ENGL

30、 L778 lbZLibb9 073822b 475 W EN IS0 10620:1998 Annex ZA (normative) Normative references to international publications with their relevant European publications This European Standard incorporates by dated or undated reference, provisions from other publications. These normative references are cited

31、 at the appropriate places in the text 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

32、of the publication referred to appies. yearm EN year IS0 1666 1996 Starch - Determination of moisture ENIS01666 1997 IS0 3696 1987 Water for analytical laboratory use - ENISO3696 1995 content - Oven-drying methods Specification and test methods 1 BS EN IS0 10520 1998 BSI 389 Chiswick High bad London

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