1、 STD.BS1 BS EN IS0 LL2Lb-ENGL 1998 Lb24669 07LLObO 634 BRITISH STANDARD Modified starch - Determination of content of carboxymethyl groups in carboxyme thy1 starch e The European Standard EN IS0 112161998 has the status of a British Standard ICs 67.180.20 NO COPYING WITHOUT BSI PERMISSION EXCEPT AS
2、PERMITTED BY COPYRIGHT LAW BS EN IS0 112 16:1998 STD-BSI BS EN IS0 LLZLb-ENGL 1998 Lb24bb9 07LLObL 570 AmdNo. BS EN IS0 11216:1998 Date Textaffected This British Standard, having been prepared under the direction of the Consumer Products and Services Sectar Board, was pubished under the authority of
3、 the Standards Board and comes into effect on 15 July 1998 Q BSI 19% National foreword This British Standard is the English language version of EN IS0 112161998. It is identical with IS0 112161998. This British Standard has been produced to fulfl WIs obiigation to publish all approved European Stand
4、ards but, because of the absence of interest in the K in the subject concerned, there has been no UK participation in the preparation of EN 11216. Any queries relating to the EN should be directed to BSI quoting the reference AWllOo. Cross-references Attention is drawn to the fact that CEN and CENEL
5、EC Stanrad. 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 hnt cover, an inside hnt cover, the EN IS0 title page, the EN IS0 foreword pa
6、ge, the IS0 title page, page ii, pages 1 to 7, the annex ZA page, an inside back cover and a back cover. Amendments issued since publication ISBN O 680 30046 3 EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN IS0 11216 May 1998 ICs 67.1 80.20 Descriptors: see IS0 dowment English version Modified
7、 starch - Determination of content of carboxymethyl groups in carboxymethyl starch (IS0 1 121 6:1998) Amidons et fcules modifis - Dtemination de la teneur en groupes carboxymthyles dans lamidon carboxym6thyl (Is0 11216:1998) Modifizierte SWke - Bestlmmung des Gehalts an CarboxymethyistBrke (IS0 1121
8、6:1998) This European Standard was approved by CEN on 14 May 1998. CEN members are bound to comply with the CENICENELEC Internai Regulations which stipulate the conditions for givingthis European Standard the status o a national standard without any aItt3fatiOn. Up-to-date lists and bibilographicel
9、references concerning such national standards may be obtained on appcation to the Central Secretariat or to any CEN member. This European Standard exists in three offidal versions (English, French, German). A version in any other language made by translation under the responsibility of a GEN member
10、into its own language and notied to the Centd Secretariat has the same status as aie offidai verdons. CEN members are the national standards bodies of Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece. Iceland, Ireland, itaiy, Luxembourg, Netherlands, Norway, Portugal, Spai
11、n, Sweden, Switzerland and United Kingdom. * * m EUROPEAN COMMCITEE EOR STANDARDIZATION COMITE EUROPEEN DE NORMALISATION EUROPISCHES KOMITEE FOR NORMUNG Cenral Seeretarkit rue de Stassait, 36 8-1050 Bni.uls O 1998 CEN AH rights of exploitation in any form and by any means resewed worldwide for CEN n
12、ational Members. Ref. No. EN IS0 11216:1998 E EN IS0 11216:1998 Foreword The text of the International Standard IS0 1 121 6:1998 has been prepared by Technical Committee ISO/TC 93 “Starch (including derivatives and by-products)“ in collaboration with CENKS. This European Standard shall be given the
13、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 CENKENELEC Internal Regulations, the national standards organizations of
14、 the following countries are bound to implement this European Standard: Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norwayflortugal, Spain, Sweden, Switzerland and the United Kingdom. Endorsement notice The text of th
15、e International Standard IS0 1 121 6:1998 was approved by CEN as a European Standard without any modification. NOTE: Normative references to International Standards are listed in annex ZA (normative). EN IS0 11216:1998 I NTE R NATIONAL STANDARD IS0 11216 First edition 1998-05-1 5 Modified starch - D
16、etermination of content of carboxymethyl groups in carboxymethyl starch Amidons et fcules modifis - Dtermination des groupes carboxymthyles dans /amidon carboxymthyle Reference number IS0 1 121 6:1998(E) STDmBSI BS EN IS0 LL2Lb-ENGL 1998 D lbZVbb9 07LLOb5 Llb D EN IS0 11216:1998 Foreword IS0 (the In
17、ternational Organization for Standardization) is a worldwide federation of national standards bodies (IS0 member bodies). The work of preparing International Standards is normally carried out through IS0 technical committees. Each member body interested in a subject for which a technical committee h
18、as been established has the right to be represented on that committee. Intemational organizations, governmental and non- governmental, in liaison with ISO, also take part in the work. IS0 collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical
19、 standardization. Draft Intemational Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. International Standard IS0 1 1216 was prepared by Techni
20、cal Committee ISOTTC 93, Starch (including derivatives and by-products). Annexes A and B of this International Standard are for information only. 0.rcriptors: carbohydrates, sterches. food starch, chemical analysis, determination of content, sodium organic compounds, volumetric analysis. i STDIBSI B
21、S EN IS0 LLZLb-ENGL L998 Lb2Libb9 07LLDbb 052 EN IS0 11216:1998 Modified starch - Determination of content of carboxymethyl groups in carboxymethyl starch 1 Scope This International Standard specifies a method for the determination of the content of carboxymethyl groups in carboxymethyl starch. The
22、method is suitable t .?determining carboxymethyl group contents between 1,6 Yo (dm) and 10,O % (dm). 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 publicatio
23、n, 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 IS0 maintain registers of
24、 currently valid International Standards. E - - * * IS0 1666:1996, Starch - Determination of moisture content - Oven-drying method. rn IS0 3696:i 987, Water for analytical laboratory use - Specification and test methods. 3 Definition For the purposes of this International Standard, the following def
25、inition applies 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 NOTE The carboxymethyl group content is expressed as a percentage by mass. 4 Principle The carboxymethyl groups are converted
26、 into the acid form 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 starc
27、h is dried and a 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. 1 STDmBSI BS EN IS0 bL2Lb-ENGL 1998 Lb24bb9 07LLOb7 Tqq EN IS0 11216:1998 5 Reagents and materials Use only reagents o
28、f recognized analytical grade. 5.1 Water, complying with at least grade 3 in accordance with IS0 3696. The water shall be free from carbon dioxide. 5.2 Methanol, 100 %. 5.3 Hydrochloric acid, c(HCI) = 4 mol/l. 5.4 Sodium hydroxide solution, c(Na0H) = 0,l mol/l, free from carbon dioxide. 5.5 Phenolph
29、thalein solution, in ethanol 90 % (VN), p(phenolphtha1ein) = 10 g/l. 5.6 Dilute hydrochloric acid, c(HCI) = 0,l 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
30、 shear, and being explosion proof. 6.4 Beakers, of capacity 500 ml. 6.5 Crucibles, sintered glass, 40 mi volume, porosity P40 (pore size index 16 pm to 40 pm). 6.6 Drying oven, capable of being maintained at a temperature of 40 OC i 2 OC, provided with air ventilation and being explosion proof. 6.7
31、Pestle and mortar. 6.8 Sieve, 800 pm. 6.9 Blade mill. 6.10 Magnetic stirrer. 7 Sampling It is important 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 Internation
32、al Standard. 8 Preparation of test sample Sieve the laboratory sample through the 800 pm sieve (6.8). If the material does not pass through the sieve, then grind the sample with a blade mill (6.9) until it passes completely through the 800 pm sieve. Homogenize the sample. 2 EN IS0 11216:1998 9 Proce
33、dure WARNING - Methanol is a key material in this analysis and is used in quite large quantities. Take all necessary safety precautions 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
34、explosion proof. In addition, disposal of waste methanol shall be in accordance with legal requirements. 9.1 Test portion Weigh, to the nearest 1 mg, about 3 g of the prepared test sample into a 150 ml beaker (6.1). 9.2 Conversion of the carboxymethyl salts Wet the test portion with 3 ml of methanol
35、 (5.2) and stir with a spatula until homogeneous. Add 75 ml of water (5.1) and stir until fully dispersed. NOTE For highly viscous starch, 6 mi of methanol and 100 ml 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 usi
36、ng the pH meter (6.2). Stir for 30 min with the stirrer (6.3). 9.3 Precipitation of the acid form Add 300 ml of methanol (5.2) into a 500 ml beaker (6.4). Pour the dissolved test portion solution dropwise into the methanol, while stirring vigorously. NOTE If the test portion is dispersed in 100 mi o
37、f water (see note in 9.2), then 400 ml of methanol has to be used to precipitate the starch. When addition is complete, continue stirring for one further minute. Cover the beaker and allow to stand for 2 h. - E _. _I - _I m - * * 9.4 Recovery of the precipitated acid form v, Decant the clear liquid
38、from the beaker, collecting it in an appropriate vessel. Filter the residue on a sintered glass crucible (6.5) under vacuum. When the precipitate is just dry, add 25 ml of methanol (5.2). Stir, and re-apply suction. Repeat this step until the pH of the filtrate is greater than 3,5. Give one final wa
39、sh with methanol. Transfer the precipitate from the crucible to a watch glass and dry for a few hours in the oven (6.6) set at 40 “C. 9.5 Test portion for titration Grind the dry precipitate in a pestle and mortar (6.7). Weigh, to the nearest 0,l mg, about 1,5 g into a 150 ml beaker (6.1). NOTE The
40、mass taken should contain between 0,5 mmol and 1,5 mmol of carboxymethyl groups. 9.6 Titration Moisten the sample with 2 ml of methanol (5.2) and add 75 ml of water (5.1) to dissolve. Warm the contents of the beaker in a boiling water bath to 90 OC. Cool to ambient temperature before continuing. Add
41、 25,OO ml of sodium hydroxide solution (5.4) to the solution. Cover the beaker with foil and stir for 1 h on a magnetic stirrer (6.1 O). 3 STD.BSI ES EN IS0 11216-ENGL 1998 m Lb24bb9 071LOb9 8bL EN IS0 11216:1998 Introduce 2 or 3 drops of phenolphthalein solution (5.5) and titrate to just colourless
42、 with dilute hydrochloric acid (5.6). NOTE 1 It the titration is performed potentiometrically, this should be performed in a closed vessel, with pH = 9,0 as endpoint. NOTE 2 If a very viscous solution is obtained for titration, up to 50 mg of sodium chloride (5.7) can be added to reduce the viscosit
43、y. 9.7 Blank titration Add 25,OO ml of sodium hydroxide solution (5.4) to a 150 ml beaker (6.1). Add 2 ml of methanol (5.2) and 75 ml of water (5.1 ). Titrate with hydrochloric acid (5.6) as described in 9.6. 9.8 Moisture content Using a test portion of about 1 g, determine the moisture content of t
44、he test portion for titration (9.5) in accordance with IS0 1666. 1 O Calculation 10.1 Calculate the carboxymethyl group content of the dry test sample by the equation : where w, is the carboxymethyl group content, in percentage by mass, of the acid-washed and dry test sample; c is the concentration,
45、 in moles per litre, of dilute hydrochloric acid (5.6) used for the titration; M, is the molar mass, in grams per mole, of the carboxymethyl function in the acid form as reacted to the starch (M, = 58 glmol); vb is the volume, in millilitres, of dilute hydrochloric acid (5.6) used for the blank titr
46、ation; V, is the volume, in millilitres, of dilute hydrochloric acid (5.6) used for the sample titration; rn is the mass, in milligrams, of the test portion for titration (9.5); w, is the moisture content, in percentage by mass, of the test sample for titration (9.5) determined in 9.8. Round the res
47、ult to the nearest 0,Ol YO (dm). 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 substitution can be calculated in the dry test sample by the equation: WC X Ma
48、(loo % - wc) x M, x, = where 4 - - STD-BSI BS EN IS0 LLELb-ENGL 1998 W 1624669 0711070 583 = EN IS0 11216:1998 x, is the degree of carboxymethyl substitution, in mole fraction, in the dry test sample; w, is the carboxymethyl group content, in percentage by mass, of the dry test sample; Ma is the mol
49、ar mass, in grams per mole, of anhydroglucose (Ma =162 g/mol); M, is the molar mass, in grams per mole, of the carboxymethyl function in the acid form as reacted to the starch (M, = 58 g/mol). 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 in annex 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 absol
