EN 14880-2005 en Surface active agents - Determination of inorganic sulphate content in anionic surface active agents - Potentiometric lead selective electrode titration method《表面活.pdf

1、BRITISH STANDARDBS EN 14880:2005Surface active agents Determination of inorganic sulphate content in anionic surface active agents Potentiometric lead selective electrode titration methodThe European Standard EN 14880:2005 has the status of a British StandardICS 71.100.40g49g50g3g38g50g51g60g44g49g4

2、2g3g58g44g55g43g50g56g55g3g37g54g44g3g51g40g53g48g44g54g54g44g50g49g3g40g59g38g40g51g55g3g36g54g3g51g40g53g48g44g55g55g40g39g3g37g60g3g38g50g51g60g53g44g42g43g55g3g47g36g58BS EN 14880:2005This British Standard was published under the authority of the Standards Policy and Strategy Committee on 26 Sep

3、tember 2005 BSI 26 September 2005ISBN 0 580 46665 5National forewordThis British Standard is the official English language version of EN 14880:2005.The UK participation in its preparation was entrusted to Technical Committee CII/34, Methods of test for surface active agents, which has the responsibi

4、lity to:A list of organizations represented on this committee can be obtained on request to its secretary.Cross-referencesThe British Standards which implement international or European publications referred to in this document may be found in the BSI Catalogue under the section entitled “Internatio

5、nal Standards Correspondence Index”, or by using the “Search” facility of the BSI Electronic Catalogue or of British Standards Online.This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application.Compliance with a British S

6、tandard does not of itself confer immunity from legal obligations. aid enquirers to understand the text; present to the responsible international/European committee any enquiries on the interpretation, or proposals for change, and keep UK interests informed; monitor related international and Europea

7、n developments and promulgate them in the UK.Summary of pagesThis document comprises a front cover, an inside front cover, the EN title page, pages 2 to 11 and a back cover.The BSI copyright notice displayed in this document indicates when the document was last issued.Amendments issued since publica

8、tionAmd. No. Date CommentsEUROPEAN STANDARDNORME EUROPENNEEUROPISCHE NORMEN 14880August 2005ICS 71.100.40English VersionSurface active agents - Determination of inorganic sulphatecontent in anionic surface active agents - Potentiometric leadselective electrode titration methodAgents de surface - Dte

9、rmination de la teneur en sulfateinorganique dans les agents de surface anioniques -Mthode potentiomtrique de titrage avec lectrode membrane slective au plombGrenzflchenaktive Stoffe - Bestimmung des Gehaltes ananorganischen Sulfaten in anionischen grenzflchenaktivenStoffen - Potentiometrische Titra

10、tion mit einer bleiselektivenElektrodeThis European Standard was approved by CEN on 8 July 2005.CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this EuropeanStandard the status of a national standard without any alteration. Up-to-da

11、te lists and bibliographical references concerning such nationalstandards 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 translationunder the re

12、sponsibility of a CEN member into its own language and notified to the Central Secretariat has the same status as the officialversions.CEN members are the national standards bodies of Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France,Germany, Greece, Hungary, Iceland, Irela

13、nd, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia,Slovenia, Spain, Sweden, Switzerland and United Kingdom.EUROPEAN COMMITTEE FOR STANDARDIZATIONCOMIT EUROPEN DE NORMALISATIONEUROPISCHES KOMITEE FR NORMUNGManagement Centre: rue de Stassart, 36 B-1050 Bru

14、ssels 2005 CEN All rights of exploitation in any form and by any means reservedworldwide for CEN national Members.Ref. No. EN 14880:2005: EEN 14880:2005 (E) 2 Contents Page Foreword 3 1 Scope .4 2 Normative references .4 3 Principle.4 4 Reagents4 5 Apparatus 5 6 Sampling and preparation of the test

15、solution .5 7 Procedure 5 8 Calculation and expression of results.7 9 Precision7 10 Test report .7 Annex A (informative) Titration apparatus settings.8 Annex B (informative) Results of inter-laboratory test 10 Bibliography.11 EN 14880:2005 (E) 3 Foreword This European Standard (EN 14880:2005) has be

16、en prepared by Technical Committee CEN/TC 276 “Surface active agents”, 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 February 2006, and conflicting nat

17、ional standards shall be withdrawn at the latest by February 2006. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, Fr

18、ance, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom. EN 14880:2005 (E) 4 1 Scope This European Standard specifies a method for the determination of the

19、content of inorganic sulphate in anionic surface active agents. It can be applied to -olefin sulphonates and n-olefin sulphonates, alcohol sulphates, alcohol ether sulphates, alkyl benzene sulphonates and other alkyl sulphonates. This method is used also for the determination of inorganic sulphate i

20、n alkyl benzene sulphonates or other alkyl sulphonates in their acid form. This method also applies to deep-coloured samples. NOTE Sulphate can be present as sulphuric acid, ionic salts of this acid or mixture of these. 2 Normative references The following referenced documents are indispensable for

21、the application of this European Standard. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. EN ISO 3696, Water for analytical laboratory use Specification and test methods (ISO 3696:1987) I

22、SO 607, Surface active agents and detergents Methods of sample division 3 Principle Potentiometric titration of the test sample containing inorganic sulphate is performed in non-aqueous medium with a lead nitrate standard volumetric solution. The reaction is the following: +342423NO2PbSOSO)NO(Pb Lea

23、d sulphate precipitate is formed during the titration and the non-aqueous medium decreases its solubility. Nitric acid is added to remove possible interference from carbonates. The endpoint is related to an increase in lead ion activity, as measured by a lead-selective electrode. 4 Reagents During t

24、he analysis, unless otherwise specified, use only reagents of recognised analytical grade that have been checked in advance as to not interfere with the analytical results. 4.1 Water, complying with grade 3 as defined in EN ISO 3696. NOTE If the water is purified via ion-exchange resins, ensure that

25、 no cationic or anionic species from the resins cause interference. 4.2 Nitric acid, solution c(HNO3) = 1 mol/l. 4.3 Lead nitrate standard volumetric solution, c(Pb(NO3)2) = 0,01 mol/l. Weigh 3,312 g of lead nitrate, previously dried at 150 C in a vacuum oven, dissolve in water, by using a small bea

26、ker. Quantitatively transfer the solution into a 1 000 ml volumetric flask and add water up to the mark. 4.4 Lead nitrate standard volumetric solution, c(Pb(NO3)2) = 0,005 mol/l. Weigh 1,656 g of lead nitrate, previously dried at 150 C in a vacuum oven, dissolve in water, by using a small beaker. Qu

27、antitatively transfer the solution into a 1 000 ml volumetric flask and add water up to the mark. EN 14880:2005 (E) 5 4.5 Potassium sulphate solution, c(K2SO4) = 0,01 mol/l. Weigh approximately 1,74 g (m) of K2SO4, previously dried in an oven at 180 C, dissolve with water in a 1 000 ml volumetric fl

28、ask, make up to the mark and homogenize. Calculate the factor, f, of the solution, according to the Equation (1): 7425,1mf = (1) where m is the mass of potassium sulphate weighted, in grams; 1,742 5 is the mass, in grams, of 0,01 mole of potassium sulphate K2SO4. 4.6 Propan-2-ol (C3H8O) 5 Apparatus

29、Ordinary laboratory apparatus and the following: 5.1 Automatic potentiometric titration apparatus, with drift-controlled data acquisition and dynamic titrimetric dosing equipped with a piston burette delivery system of 20 ml capacity. 5.2 Lead-selective electrode (Metrohm 6.0502.1701), or similar).

30、5.3 Reference electrode Ag/AgCl filled with a saturated sodium nitrate ethanolic solution. 6 Sampling and preparation of the test solution 6.1 Sampling The laboratory sample shall be taken and stored in accordance with ISO 607. 6.2 Preparation of the test solution For non-homogeneous products, it wi

31、ll be better to dissolve a large sample (for example 5 g) in a suitable solvent (for example propan-2-ol/water) and take an aliquot for the titration. Exactly weigh, in a 150 ml beaker, a quantity of the sample (m0) so as to consume a maximum of 10 ml of Pb(NO3)2solution (4.3 or 4.4) during the titr

32、ation (typically, the mass is in the range 0,3 g to 1 g). 7 Procedure 7.1 Standardisation of the lead nitrate standard volumetric solution Pipette 5,00 ml of the potassium sulphate solution (4.5) into a 150 ml beaker. Add approximately 1 ml of nitric acid solution (4.2) and 100 ml of propan-2-ol (4.

33、6). 1) Metrohm 6.0502.170 is the trade name of instruments supplied by Metrohm ltd. (CH-9101 Herisau, Switzerland). This information is given for the convenience of users of this European Standard and does not constitute an endorsement by CEN of these instruments named. EN 14880:2005 (E) 6 Prepare t

34、he potentiometer (5.1) for operation, immerse the electrodes in the solution and stir by using the electromagnetic stirrer. Titrate with the lead nitrate volumetric solution (4.3 or 4.4). Record the reagent consumption, V2, at the inflection point of the titration curve. NOTE An example for instrume

35、nt settings and a titration curve are given in Annex A. Run the standardization in triplicates. The concentration of the lead nitrate standard volumetric solution, ca, expressed in moles per litre is calculated in accordance with the following Equation (2): 21VfcVca=(2) where V1is the volume of pota

36、ssium sulphate solution (4.5), in millilitres; c is the concentration of the lead nitrate solution, in moles per litre; f is the factor of the potassium sulphate solution determined according to 4.5; V2is the average volume of lead nitrate standard volumetric solution used in the titration, in milli

37、litres. NOTE In alternative, a solution of sulphuric acid, c(H2SO4)= 0,01 mol/l, can be used to standardize the lead nitrate solution. In this case the sulphuric acid solution can be prepared diluting in the suitable ratio a standard reagent. 7.2 Determination If the expected sulphate content is low

38、er than 1% m/m, use the Pb(NO3)2, c(Pb(NO3)2)= 0,005 mol/l for the titration, otherwise use the Pb(NO3)2, c(Pb(NO3)2)= 0,01 mol/l. Exactly weigh, in a 150 ml beaker, a quantity of the sample (m0) so as to consume a maximum of 10 ml of Pb(NO3)2 standard volumetric solution during the titration. NOTE

39、Weighing more than 1g of surfactant should be avoided because the electrical behaviour of the ion-selective electrode is strongly dependent on the surfactant concentration and could give bad potentiometric curves. Approximately 1 ml of nitric acid solution (4.2) and 100 ml of propan-2-ol (4.6) shoul

40、d be added. The solution should be acidic (lower than pH 3) before titration. If 1 ml of nitric acid solution (4.2) is not sufficient to achieve this, more acid should be added. Prepare the potentiometer (5.1) for operation, immerse the electrodes in the solution and stir by using the electromagneti

41、c stirrer. Titrate with the lead nitrate volumetric solution (4.3 or 4.4). Record the reagent consumption, V, at the inflection point of the titration curve Clean the ion-selective electrode tip before each titration by using a soft cloth or paper together with propan-2-ol. EN 14880:2005 (E) 7 8 Cal

42、culation and expression of results The content of inorganic sulphate in the sample, cb, expressed in percent by mass of sodium sulphate (Na2SO4) is calculated according to the Equation (3): 1004,1420=mVccab(3) where m0is the mass of the test sample, in grams; cais the concentration of the lead nitra

43、te standard volumetric solution , in moles per litre; V is the average volume consumption of lead nitrate standard volumetric solution. NOTE The value 142,04 is the molecular mass of Na2SO4in grams. 9 Precision 9.1 Repeatability limit The absolute difference between two independent single test resul

44、ts, 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, will not exceed the repeatability limit, r, in more than 5 % of cases. Precision data are given in Annex B. 9.2 Reproducibility limit Th

45、e absolute difference between two independent single test results, obtained using the same method on identical test material in different laboratories by different operators using different equipment, will not exceed the reproducibility limit, R, in more than 5 % of cases. Precision data are given i

46、n Annex B. 10 Test report The test report shall include the following information: a) all necessary information for the complete identification of the sample; b) method used (a reference to this European Standard, i.e. EN 14880); c) test results; d) details of any operations not specified in this Eu

47、ropean Standard or in the standards to which reference is made, and any operations regarded as optional, as well as any incidents likely to have affected the results. EN 14880:2005 (E) 8 Annex A (informative) Titration apparatus settings A.1 Automatic potentiometric titration apparatus The following

48、 parameters are the settings for the automatic potentiometric titration apparatus and are intended to act as a guideline, only (see Table A.1). The titration is carried out with dynamic dosing. For samples of known concentration providing a suitable starting volume can shorten the titration time. Ta

49、ble A.1 Instrument settings Parameter Set point Start volume 0 ml Measuring point density 2 Signal drift 20 mV/min Equilibration time 38 s Minimum increment 10 l Burette volume/resolution 20 ml/2 l Dose rate, max. 2 ml/min Pause 300 sEvaluation end point criteria 5 NOTE 1 The parameter “Start volume” can be changed depending on the final titration volume of the lead nitrate solution. For instance, if the final titration volume is higher than 4 ml or 5 ml, “Start volume” can be set to 2 ml (that is just to save time). NOTE 2 The parameter “Pause” i