BS EN ISO 11216-1998 Modified starch - Determination of content of carboxymethyl groups in carboxymethyl starch《改良淀粉 羧甲基淀粉中羧甲基团含量的测定》.pdf

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1、BRITISH STANDARD BS EN ISO 11216:1998 Modified starch Determination of content of carboxymethyl groups in carboxymethyl starch The European Standard EN ISO11216:1998 has the status of a British Standard ICS 67.180.20BSENISO11216:1998 This British Standard, having been prepared under the directionof

2、the Consumer Products and Services Sector Board, was published under the authority of the Standards Boardand comes into effect on 15 July 1998 BSI 04-1999 ISBN 0 580 30046 3 National foreword This British Standard is the English language version of EN ISO 11216:1998. It is identical with ISO 11216:1

3、998. This British Standard has been produced to fulfil BSIs obligation to publish all approved 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 11216. Any queries relating to the EN should be di

4、rected to BSI quoting the reference AW/100. Cross-references Attention is drawn to the fact 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 in

5、ternational or European publications referred to in this document may be found in the BSI Standards Catalogue under the section entitled “International Standards Correspondence Index”, or by using the “Find” facility of the BSI Standards Electronic Catalogue. A British Standard does not purport to i

6、nclude 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 front cover, pa

7、ges i and ii, theEN ISO title page, page 2, the ISO title page, page ii, pages 1 to 4, aninsideback 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. Amendment

8、s issued since publication Amd. No. Date CommentsBSENISO11216:1998 BSI 04-1999 i Contents Page National foreword Inside front cover Foreword 2 Foreword ii Text of ISO 11216 1ii blankEUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN ISO 11216 May 1998 ICS 67.180.20 Descriptors: See ISO document En

9、glish version Modified starch Determination of content of carboxymethyl groups in carboxymethyl starch (ISO 11216:1998) Amidons et fcules modifis Dtermination de la teneur en groupes carboxymthyles dans lamidon carboxymthyl (ISO 11216:1998) Modifizierte Strke Bestimmung des Gehalts an Carboxymethyls

10、trke (ISO 11216:1998) This European Standard was approved by CEN on 14 May 1998. 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 without any alteration. Up-to-date lists and b

11、ibliographical 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 language made by translation under the responsibilit

12、y 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, Iceland, Ireland, Italy, Luxembourg, Netherlands

13、, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom. CEN European Committee for Standardization Comit Europen de Normalisation Europisches Komitee fr Normung Central Secretariat: rue de Stassart 36, B-1050 Brussels 1998 CEN All rights of exploitation in any form and by any means reserv

14、ed worldwide for CEN national Members. Ref. No. EN ISO 11216:1998 EENISO11216:1998 BSI 04-1999 2 Foreword The text of the International Standard ISO11216:1998 has been prepared by Technical Committee ISO/TC 93 “Starch (including derivatives and by-products)” in collaboration with CEN/CS. This Europe

15、an Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by November 1998, and conflicting national standards shall be withdrawn at the latest by November 1998. According to the CEN/CENELEC Internal Regulations, the nat

16、ional standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, CzechRepublic, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and the United Kingdom. E

17、ndorsement notice The text of the International Standard ISO11216:1998 was approved by CEN as a European Standard without any modification. NOTENormative references to International Standards are listed inAnnex ZA (normative). Contents Page Foreword 2 1 Scope 1 2 Normative references 1 3 Definition

18、1 4 Principle 1 5 Reagents and materials 1 6 Apparatus 1 7 Sampling 1 8 Preparation of test sample 1 9 Procedure 1 10 Calculation 2 11 Precision 3 12 Test report 3 Annex A (informative) Results of an interlaboratory trial 4 Annex B (informative) Bibliography 4 Annex ZA (normative) Normative referenc

19、es to international publications with their relevant publications Inside back cover Table A.1 4ENISO11216:1998 ii BSI 04-1999 Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing Internatio

20、nal Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO

21、, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an Inte

22、rnational Standard requires approval by at least 75 % of the member bodies casting a vote. International Standard ISO 11216 was prepared by Technical Committee ISO/TC 93, Starch (including derivatives and by-products). Annex A and Annex B of this International Standard are for information only. Desc

23、riptors: Carbohydrates, starches, food starch, chemical analysis, determination of content, sodium organic compounds, volumetric analysis.ENISO11216:1998 BSI 04-1999 1 1 Scope This International Standard specifies a method for the determination of the content of carboxymethyl groups in carboxymethyl

24、 starch. The method is suitable for determining carboxymethyl group contents between 1,6 % (m/m) and 10,0 % (m/m). 2 Normative references The following standards contain provisions which, through reference in this text, constitute provisions of this International Standard. At the time of the publica

25、tion, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on the International Standard are encouraged to investigate the possibility of applying the most recent editions of the standards indicated below. Members of IEC and ISO maintain registers

26、 of currently valid International Standards. ISO 1666:1996, Starch Determination of moisture content Oven-drying method. ISO 3696:1987, Water for analytical laboratory use Specification and test methods. 3 Definition For the purposes of this International Standard, the following definition applies.

27、3.1 carboxymethyl group content mass of carboxymethyl groups in the acid form divided by the mass of the test portion of carboxymethyl starch in the acid form NOTEThe carboxymethyl group content is expressed as a percentage by mass. 4 Principle The carboxymethyl groups are converted into the acid fo

28、rm by acidifying a solution or a suspension of the starch with hydrochloric acid. After the starch is precipitated with methanol, it is allowed to settle before being filtered off on a sintered glass crucible. The excess acid is completely removed by washing with methanol. The starch is dried and a

29、weighed portion is treated with a measured excess of sodium hydroxide solution. The sodium hydroxide not used by the sample is back-titrated with hydrochloric acid. 5 Reagents and materials Use only reagents of recognized analytical grade. 5.1 Water, complying with at least grade 3 in accordance wit

30、h ISO3696. The water shall be free from carbon dioxide. 5.2 Methanol, 100 %. 5.3 Hydrochloric acid, c(HCl) = 4 mol/l. 5.4 Sodium hydroxide solution, c(NaOH) = 0,1 mol/l, free from carbon dioxide. 5.5 Phenolphthalein solution, in ethanol 90% (V/V), (phenolphthalein) = 10 g/l. 5.6 Dilute hydrochloric

31、acid, c(HCl) = 0,1 mol/l. 5.7 Sodium chloride. 6 Apparatus Usual laboratory apparatus and, in particular, the following. 6.1 Beakers, of capacity 150 ml. 6.2 pH meter. 6.3 Mechanical stirrer, capable of high shear, and being explosion proof. 6.4 Beakers, of capacity 500 ml. 6.5 Crucibles, sintered g

32、lass, 40ml volume, porosity P40 (pore size index 16 4m to 404m). 6.6 Drying oven, capable of being maintained at a temperature of 40C 2C, provided with air ventilation and being explosion proof. 6.7 Pestle and mortar. 6.8 Sieve, 8004m. 6.9 Blade mill. 6.10 Magnetic stirrer. 7 Sampling It is importan

33、t that the laboratory receive a sample which is truly representative and has not been damaged or changed during transport or storage. Sampling is not part of the method specified in this International Standard. 8 Preparation of test sample Sieve the laboratory sample through the 8004m sieve (6.8). I

34、f the material does not pass through the sieve, then grind the sample with a blade mill (6.9) until it passes completely through the 8004m sieve. Homogenize the sample. 9 Procedure WARNING Methanol is a key material in this analysis and is used in quite large quantities. Take all necessary safety pr

35、ecautions because of the toxicity and flammability of methanol. Carry out all work in an explosion-proof fume cupboard. All mechanical and electrical equipment used shall be explosion proof. In addition, disposal of waste methanol shall be in accordance with legal requirements.ENISO11216:1998 2 BSI

36、04-1999 9.1 Test portion Weigh, to the nearest 1mg, about 3g of the prepared test sample into a 150ml beaker (6.1). 9.2 Conversion of the carboxymethyl salts Wet the test portion with 3ml of methanol (5.2) and stir with a spatula until homogeneous. Add 75ml of water (5.1) and stir until fully disper

37、sed. NOTEFor highly viscous starch, 6 ml of methanol and 100ml of water can be used to give a solution which can be easily stirred. Acidify this solution with hydrochloric acid (5.3) to pH = 1 using the pH meter (6.2). Stir for 30 min with the stirrer (6.3). 9.3 Precipitation of the acid form Add 30

38、0ml of methanol (5.2) into a 500ml beaker(6.4). Pour the dissolved test portion solution dropwise into the methanol, while stirring vigorously. NOTEIf the test portion is dispersed in 100ml of water (seenote in9.2), then 400ml of methanol has to be used to precipitate the starch. When addition is co

39、mplete, continue stirring for one further minute. Cover the beaker and allow to stand for 2h. 9.4 Recovery of the precipitated acid form Decant the clear liquid from the beaker, collecting it in an appropriate vessel. Filter the residue on a sintered glass crucible (6.5) under vacuum. When the preci

40、pitate is just dry, add 25ml of methanol (5.2). Stir, and re-apply suction. Repeat this step until the pH of the flitrate is greater than 3,5. Give one final wash with methanol. Transfer the precipitate from the crucible to a watch glass and dry for a few hours in the oven (6.6) set at40C. 9.5 Test

41、portion for titration Grind the dry precipitate in a pestle and mortar(6.7). Weigh, to the nearest 0,1mg, about 1,5g into a150ml beaker (6.1). NOTEThe mass taken should contain between 0,5mmol and1,5mmol of carboxymethyl groups. 9.6 Titration Moisten the sample with 2ml of methanol (5.2) and add 75m

42、l of water (5.1) to dissolve. Warm the contents of the beaker in a boiling water bath to90C. Cool to ambient temperature before continuing. Add 25,00 ml of sodium hydroxide solution (5.4) to the solution. Cover the beaker with foil and stir for1h on a magnetic stirrer (6.10). Introduce 2 or 3 drops

43、of phenolphthalein solution(5.5) and titrate to just colourless with dilute hydrochloric acid (5.6). NOTE 1If the titration is performed potentiometrically, this should be performed in a closed vessel, with pH = 9,0 as endpoint. NOTE 2If a very viscous solution is obtained for titration, up to50mg o

44、f sodium chloride (5.7) can be added to reduce the viscosity. 9.7 Blank titration Add 25,00 ml of sodium hydroxide solution (5.4) to a150ml beaker (6.1). Add 2ml of methanol (5.2) and 75ml of water (5.1). Titrate with hydrochloric acid (5.6) as described in9.6. 9.8 Moisture content Using a test port

45、ion of about 1g, determine the moisture content of the test portion for titration(9.5) in accordance with ISO 1666. 10 Calculation 10.1 Calculate the carboxymethyl group content of the dry test sample by the equation: where w c is the carboxymethyl group content, in percentage by mass, of the acid-w

46、ashed and dry test sample; c is the concentration, in moles per litre, of dilute hydrochloric acid (5.6) used for the titration; M c is the molar mass, in grams per mole, of the carboxymethyl function in the acid form as reacted to the starch (M c= 58g/mol); V b is the volume, in millilitres, of dil

47、ute hydrochloric acid (5.6) used for the blank titration; V s is the volume, in millilitres, of dilute hydrochloric acid (5.6) used for the sample titration; m is the mass, in milligrams, of the test portion for titration (9.5); w m is the moisture content, in percentage by mass, of the test sample

48、for titration (9.5) determined in9.8.ENISO11216:1998 BSI 04-1999 3 Round the result to the nearest 0,01% (m/m). 10.2 The result may be calculated as the degree of carboxymethyl substitution, which is defined as the ratio of moles of carboxymethyl per mole anhydroglucose. The degree of carboxymethyl

49、substitution can be calculated in the dry test sample by the equation: where In this case, the result should be rounded to the nearest 0,001 unit. 11 Precision 11.1 Interlaboratory test Details of an interlaboratory test on the precision of the method are summarized inAnnex A. The values derived from this interlaboratory test may not be applicable to concentration ranges and matrices other than those given. 11.2 Repeatability The absolute difference between two independent single test results, obtained using the same method on identical test