1、 STDaBSI BS EN IS0 LLZLLI-ENGL 177b W LbZLIbbS 0575382 2T8 BRITISH STANDARD Modified starch - Determination of carboxyl group content of oxidized starch * * u3 The European Standard EN IS0 11214 : 1996 has the status of a British Standard ICs 67.180.20 NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PER
2、MITTED BY COPYRIGH LAW BS EN IS0 11214 : 1996 BS EN IS0 11214 : 1996 Amd. No. This British Standard was published under the authority of the Standards Board and comes into effect on 15 December 1996 O BSI 1996 Date Text affected Amendments issued since publication The following BSI references relate
3、 to the work on this standard: Committee reference AW/lOO Draft for comment 94607891 DC I I ISBN O 680 26077 1 STD-BSI BS EN IS0 1121q-ENGL 177b m Lb2LfbbS 057538q O70 m BS EN IS0 11214 : 1996 Contents Committees responsible Page Inside front cover National foreword ii Foreword 2 Method 1 Scope 3 2
4、Normative references 3 Principle 4 Reagents and materiais 3 3 3 6 7 Procedure Preparation of the test sample 4 4 8 Expression of results 4 9 Precision 5 10 Testreport 5 Annexes A (informative) Untitled 6 ZA (normative) Normative references to intemational pubiications with their relevant European pu
5、blications 8 Table A.l StaWical results of the interlaboratory test 6 B (informative) Bibiiogmphy 7 O BSI 1996 i STD-BSI BS EN IS0 LLZLLi-ENGL 177b = Lb24bbS 0575385 TO7 BS EN IS0 11214 : 1996 National foreword This British Standard has been prepared under the direction of the BSI Standards Board an
6、d is the English anguage version of EN 11214 : 1996 Modified starch - Detemzinatwn of carboxgl pup content of oxiized starch, published by the European Committee for Standardization (CEN). It is identical with IS0 11214 : 1996, published by the Inmationai Organization for Standadzation (ISO). This B
7、ritish standard has been produced to fulfil BSIs obigation to publish aii 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 IS0 11214. Any queries reUng to the EN should be directed to B
8、SI quoting the reference AW/l. Cross-references Publication referred to Normative EN IS0 1666 : 1994 EN IS0 3696 : 1995 ENISO3946: 1994 Informative IS0 57251 : 1994 IS0 57252 : 1994 Corresponding British Standard BS EN IS0 1666 : 1994 StuEh. Determination of moisture content. hen-dcring methods BS E
9、N IS0 3696 : 1995 Water for analytical labomtory use. Smatkn and test methods BS EN IS0 3946 : 1994 Starches an deriveional standards shall be withdrawn at the latest by January 1997. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following couniries a
10、re bound to implement this European Standard: Austria, Belgium, Denmark, Fnland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and the United Kingdom. O BSI 1996 Page 3 EN IS0 11214 : 1996 Modified starch - Determination of ca
11、rboxyl group content of oxidized starch 1 Scope This International Standard specifies a method for the determination of the carboxyl group content of oxidized starch. The method is suitable for determining carboxyl group contents up to 1 % (m/m). II E - - 2 Normative references - - e The following s
12、tandards contain provisions which, through reference in this text, constitute provisions of this International Standard. At the time of publi- cation, the editions indicated were valid. All standards are subject to revision, and patties to agreements based on this International Standard are encourag
13、ed to investigate the possibility of appiying the most re- cent editions of the standards indicated below. Members of IEC and IS0 maintain registers of cur- rently valid International Standards. * * v IS0 1666:-”, Starch - Determination of moisture content - Ovendrying method. IS0 3696: 1987, Wafer
14、for analytical laboratory use - Specification and fest methods. IS0 3946: 1982, Starches and derived products - Determination of total phosphorus content - Spectrophotometric method. 3 Principle The carboxyl groups are converted into the acid form by adding a mineral acid to a homogenized test por-
15、tion of the oxidized starch. The cations and the excess acid are eliminated by washing with water. The washed sample is gelatinized and titrated with sodium hydroxide standard solution. For oxidized potato starch, the result is corrected for the phosphate group content. 4 Reagents and materials Use
16、only reagents of recognized analytical grade, un- less otherwise specified, and water complying with grade 2 in accordance with IS0 3696. The water used shall be free of carbon dioxide. 4.1 Hydrochloric acid, O, 1 mol/l solution. 4.2 Sodium hydroxide, standard volumetric sol- ution, c(Na0H) = 0,l mo
17、l/l, free of carbon dioxide. 4.3 Phenolphthalein in ethanol, 1 g/i solution 90 % (VIV. 4.4 Silver nitrate, 10 g/i solution. 5 Apparatus Usual laboratory apparatus and in particular the fol- lowing. 5.1 Beakers, of capacity 100 ml and 600 ml. 5.2 Magnetic stirrer. 1) To be published. (Revision of IS0
18、 1666:1973) STD.BSI BS EN IS0 LL214-ENGL 1996 = LbZqbb9 0575389 b52 Page 4 EN IS0 11214 : 1996 5.3 Vacuum filter, equipped with a fritted glass crucible of medium porosity, or a Bchner funnel, of diameter 55 mm, equipped with a small, round filter paper (medium filtration rate). 5.4 Boiling water ba
19、th. 5.5 Mechanical stirrer. 5.6 Blade mill. 5.7 Test sieve, of aperture size 800 pm. 6 Preparation of the test sample Pass the sample through the test sieve (5.7). If the sample does not pass through the sieve, grind it using the blade mill (5.6) so that it completely passes through the sieve. Homog
20、enize the sample. NOTE 1 In the case of oxidized maize or wheat starch, it may be desirable to defat the sample by Soxhlet extraction with a mixture of propanol and water 3 + 1 (V/V) in order to correct for the contribution of lipids to the carboxyl group content. 7 Procedure 7.1 Test portion Weigh,
21、 to the nearest 0,l rng, 5 g of the test sample into a 100 ml beaker (5.1). 7.2 Conversion of the carboxyl salts Add 25 ml of the hydrochloric acid solution (4.1 ) to the beaker and stir for 30 min on the magnetic stirrer (5.2). 7.3 Washing Filter the suspension under vacuum through a fritted glass
22、crucible or Bchner funnel (see 5.3). Wash the cake obtained with water until the filtrate contains no chloride ions. Test for the absence of chloride ions by adding 1 ml of the silver nitrate solution (4.4) to 5 ml of filtrate. Turbidity or precipitation occurs within 1 min if chloride is present. W
23、ashing the cake will take approximately 300 ml of water. 7.4 Gelatinization Quantitatively transfer the cake obtained into a 600 ml beaker (5.1) with 100 ml of water. Add 200 rnl of water, place the beaker in the boiling water bath (5.4). stir continuously with the mechanical stirrer (5.5) until the
24、 starch gelatinizes and continue stirring for another 15 min. NOTES 2 Direct heating with a hotplate or Bunsen burner may overheat or scorch the material which will lead to higher results. 3 A complete gelatinization makes rapid titration easier and increases the sensitivity of the detection of the
25、end- point. 7.5 Titration Remove the beaker from the boiling bath and titrate while still hot with the sodium hydroxide solution (4.2). using the phenolphthalein solution (4.3) as indi- cator until a persistent pink colour is obtained. NOTE 4 electrometrically. The end-point (at pH = 8,3) may be det
26、ermined 7.6 Determination of moisture content Determine the moisture content of the test sample in accordance with IS0 1666. 7.7 Determination of phosphorus content For oxidized potato starch, determine the phosphorus content, wp, in percentage by mass, of the test sample in accordance with IS0 3946
27、. 8 Expression of results 8.1 Calculation Calculate the carboxyl group content, based on the dry substance, using the equation cVMC x 100 1 O0 X m 100 - w, wc = where wC is the total carboxyl group content, in per- centage by mass, based on the dry sub- stance; is the concentration, in moles per lit
28、re, of sodium hydroxide solution used for the titration; c V is the volume, in millilitres, of sodium hy- droxide solution used for the titration; Mc is the relative molecular mass of the carboxyl function (MC = 0,045); Page 6 EN IS0 11214 : 1996 m is the mass, in grams, of the test portion (7.1); i
29、s the moisture content, in percentage by mass, of the test sample. The probability level is 95 OJO when the repeatability and reproducibility limits are obtained. w, 9.1 Repeatability NOTE 5 The lipid content of maize and wheat starch contributes to the value obtained for the carboxyl group content
30、by approximately 0,l % (rnlrn). In the case of oxidized maize or wheat starch, the total carboxyl group content may be corrected for, if desired, either by deducting 0,l % (rn/m) from wc or by determining w, of a test sample which has been defatted by Soxhlet extraction with a mix- ture of propanol
31、and water 3 + 1 (V/V) (see also note 1). The absolute difference between two independent test results, obtained using the same method on identical test material in the same laboratory by the same operator using the same equipment within a short interval of time, should not be greater than 6 % of the
32、 higher of the two results. 8.2 Correction for phosphate groups 9.2 Reproducibility The phosphate groups attached to oxidized potato The absolute difference between two independent starch contribute to the value obtained for the carboxyl group content. For oxidized potato starch, 8.1 by deducting 3w
33、p from we NOTE 6 following calculation: test results, obtained using the same method on identical test material in different laboratories with not be greater than 16 96 of the higher of the two results. correct the total group content from different operators using different equipment, should The co
34、rrection quantity, 3wp, is derived from the MC 3wp z n x - x wp MP 10 Test report The test report shall specify - rn E - - where - - E wp is the phosphorus content, in percentage by * a) a reference to this International Standard; * n is the number of free acid groups left on mass, of the test sampl
35、e, obtained in 7.7; phosphorus (n = 2); b) the method used; function (M, = 0.045); m Mc is the relative molecular mass of the carboxyl c) the result(s) obtained; d) if the repeatability has been checked, the final quoted result obtained. Mp is the relative molecular mass of phosphorus (Mp = 0,031 1.
36、 It shall also mention all operating details not specified 9 Precision in this International Standard, or regarded as optional, together with details of any incidents which may have The precision of the method was established by an influenced the test result(s). interlaboratory test carried out in a
37、ccordance with IS0 5725-2 (reference 2 in annex BI. See annex A The test report shall include all information necessary for a summary of the statistical results of this test. for the complete identification of the sample. STD-BSI BS EN IS0 LLZLq-ENGL L77L m Lb24bb7 0575373 ZOO Parameter Number of la
38、boratories retained after eliminating outliers Page 6 EN IS0 11214 : 1996 M1 M2 6 6 Annex A (informative) Reproducibility standard deviation, s, % m/m) Reproducibility relative standard deviation, YO Reproducibility limit, R = 2,8 x s, % ( Fax: O181 996 7400. BSI offers members an individual updatin
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