1、 g49g50g3g38g50g51g60g44g49g42g3g58g44g55g43g50g56g55g3g37g54g44g3g51g40g53g48g44g54g54g44g50g49g3g40g59g38g40g51g55g3g36g54g3g51g40g53g48g44g55g55g40g39g3g37g60g3g38g50g51g60g53g44g42g43g55g3g47g36g58agents Potentiometric two-phase titration methodThe European Standard EN 14480:2004 has the status
2、of a British StandardICS 71.100.40Surface active agents Determination of anionic surface active BRITISH STANDARDBS EN 14480:2004Incorporating Corrigendum No. 1BS EN 14480:2004This British Standard was published under the authority of the Standards Policy and Strategy Committee on 2 December 2004 BSI
3、 2006ISBN 0 580 44937 8request 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 “International Standards Correspondence Index”, or by using the “Sear
4、ch” 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 Standard does not of itself confer immunity from legal obli
5、gations.Summary of pagesThis document comprises a front cover, an inside front cover, the EN title page, pages 2 to 14, an inside back cover and a back cover.The BSI copyright notice displayed in this document indicates when the document was last issued.Amendments issued since publicationAmd. No. Da
6、te Comments16476 Corrigendum No. 130 June 2006 Correction to 4.10A list of organizations represented on this committee can be obtained on present to the responsible international/European committee any enquiries on the interpretation, or proposals for change, and keep the UK interests informed; moni
7、tor related international and European developments and promulgate them in the UK.National forewordThis British Standard is the official English language version of EN 14480:2004, including Corrigendum May 2006.The UK participation in its preparation was entrusted to Technical Committee CII/34, Meth
8、ods of test for surface active agents, which has the responsibility to: aid enquirers to understand the text;EUROPEAN STANDARDNORME EUROPENNEEUROPISCHE NORMEN 14480September 2004ICS 71.100.40 Incorporating Corrigendum May 2006English versionSurface active agents - Determination of anionic surface ac
9、tiveagents - Potentiometric two-phase titration methodAgents de surface - Dtermination des agents de surfaceanioniques - Mthode potentiomtrique de titrage dansdeux phasesGrenzflchenaktive Stoffe - Bestimmung von anionischengrenzflchenaktiven Stoffen - PotentiometrischeZweiphasen-TitrationThis Europe
10、an Standard was approved by CEN on 1 July 2004.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-date lists and bibliographical references concernin
11、g 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 responsibility of a CEN member into its own languag
12、e 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, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta,
13、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 Brussels 2004 CEN All rights of exploitation in any
14、form and by any means reservedworldwide for CEN national Members.Ref. No. EN 14480:2004: EEN 14480:2004 (E) 2 Contents page Foreword. 3 1 Scope . 4 2 Normative references . 4 3 Principle. 4 4 Reagents 4 5 Apparatus 6 6 Sampling and preparation of the test solution 6 7 Procedure 6 8 Calculation and e
15、xpression of results 8 9 Precision 8 10 Test report . 8 Annex A (informative) Titration apparatus settings. 9 Annex B (informative) Potentiometric two-phase titration - typical titration curve 11 Annex C (informative) Results of interlaboratory test. 12 Bibliography . 14 EN 14480:2004 (E) 3 Foreword
16、 This document (EN 14480:2004) has been 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
17、by March 2005, and conflicting national standards shall be withdrawn at the latest by March 2005. 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
18、, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom. EN 14480:2004 (E) 4 1 Scope This document specifies a method for the
19、 determination of the content of anionic surface active agents in raw materials, defined as being the amount of anionic surface active agents expressed in millimoles per 100 g of product. NOTE 1 The applicability in products different than those tested should be checked in each particular case. NOTE
20、 2 In comparison to usual laboratory two-phase titration with visual endpoint determination (see ISO 2271) potentiometric titration offers the advantage of automation, operator-dependent differences in recognising the equivalence point can be neglected, and a non-critical solvent replaces the toxico
21、logically critical chloroform. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) appl
22、ies. prEN 14670, Surface active agents - Sodium dodecyl sulfate - Analysis method EN ISO 3696, Water for analytical laboratory use - Specification and test methods (ISO 3696:1987) ISO 607, Surface active agents and detergents - Methods of sample division 3 Principle Anionic surface active agents are
23、 combined with cationic surface active agents to form water-insoluble ion pairs, which are immediately extracted into a water immiscible organic solvent. This fundamental reaction is the basis for the titration of equivalents of ionic surface active agents with an oppositely charged surface active a
24、gent standard volumetric solution in the two-phase titration. This process is supported by intensively stirring the two-phase mixture of aqueous solution and organic phase. The potential which is formed in the emulsion during the titration, is recorded with the help of a solvent-resistant surface ac
25、tive agent sensitive electrode in combination with a silver/silver chloride reference electrode against the amount of titrant added. The equivalence point of the added cationic surface active agent corresponds to that one of the test solution at the inflection point of the titration curve (Annex B).
26、 4 Reagents 4.1 General WARNING Your attention is drawn to the regulations covering the handling of hazardous substances. Technical, organisational and personal protection measures should be observed. During the analysis, unless otherwise specified, use only reagents of recognized analytical grade a
27、nd have been checked in advance as to not interfere with the analytical results and water complying with grade 3 as defined in EN ISO 3696. If the water is purified via ion-exchange resins, ensure that no cationic or anionic species from the resins cause interference. 4.2 Sodium dodecyl sulfate, C12
28、H25OSO3Na, w(C12H25OSO3Na) 99 % as determined following the method prEN 14670 EN 14480:2004 (E) 5 4.3 Anionic surface active agent standard volumetric solution, ca(C12H25OSO3Na) = 0,005 mol/l Weigh 1,455 g of sodium dodecyl sulfate (sodium lauryl sulfate) (4.2) with a known active content to the nea
29、rest 1 mg in a conical flask and dissolve in about 500 ml water. Transfer quantitatively the solution into a 1000 ml volumetric flask, make up to the mark with water and mix well. The concentration of the anionic surface active agent standard volumetric solution (ca) expressed in millimoles per mill
30、ilitre is calculated in accordance with the following equation (1): 100a= Mwmc (1) where m is the mass of sodium dodecyl sulfate (4.2) in grams; w is the active matter content of sodium dodecyl sulfate (4.2) in grams per 100 g; M is the molar mass of sodium dodecyl sulfate, in grams per mole (288,4
31、g/mol). 4.4 Benzethonium chloride (CAS number: 121-54-0), C27H42ClNO2, w(C27H42ClNO2) 99 %. NOTE Benzethonium chloride is the short name for benzyldimethyl-2-2-p(1,1,3,3 tetramethyl-butyl)-phenoxy-ethoxy ethylammonium chloride. 4.5 Cationic surface active agent, standard volumetric solution, c = 0,0
32、05 mol/l: Weigh 2,2 g to 2,3 g of benzethonium chloride (4.4) to the nearest 1 mg in a conical flask and dissolve it in about 500 ml water. Transfer quantitatively the solution into a 1 000 ml volumetric flask, make up to the mark with water and mix well. Standardize the solution as specified in 7.1
33、. Standardize the cationic surface active agent solution (4.5) only when the solution has reached its equilibrium, i.e. after standing for at least one day. NOTE Cationic surface active agents as benzethonium chloride adsorb on glass surfaces like such of the burette and reagent bottle of the titrat
34、ion unit. 4.6 Potassium chloride solution, KCl, c(KCl) = 3 mol/l. 4.7 Sulfuric acid, H2SO4, c(1/2 H2SO4) = 0,5 mol/l or Hydrochloric acid, HCl, c(HCl) = 0,5 mol/l. 4.8 Emulsifier (TEGO Add1). NOTE The emulsifier has the task of supporting the formation of a stable emulsion and at the same time of pr
35、eventing the deposition of the ion associate formed during the titration on the electrode surface. 4.9 Ethanol denatured 96 % (v/v). 4.10 Methyl isobutyl ketone (MIBK), (CAS number: 108.10.1), 4-Methyl-2-pentanone, w (C6H12O) 99 %. 4.11 MIBK/ethanol-mixture Measure 500 ml MIBK (4.10) and 500 ml etha
36、nol using a volumetric cylinder, transfer into a 1l flask and mix well. 1) TEGO Add is the trade name of a product supplied by Metrohom Ltd. (CH-9101 Herisau, Switzerland). This information is given for the convenience of users of this document and does not constitute an endorsement by CEN of this p
37、roduct. Equivalent product may be used if it can be shown to lead to the same results. EN 14480:2004 (E) 6 5 Apparatus 5.1 General Ordinary laboratory apparatus and the following. 5.2 Automatic potentiometric titration apparatus, with drift controlled data acquisition and dynamic titrimetric dosing
38、equipped with 20 ml piston burette. 5.3 Propeller stirrer equipment In a potentiometric two-phase titration a thorough blending is required. Hence, a stirring propeller is compulsory. The stirrer should be constructed so that an optimal emulsification of the vessel contents is achieved with a simult
39、aneous low degree of air entrapment. Propeller stirrers shaped like ship screws have proven effective, while magnetic stirrers are not suitable. It is advisable to pay special attention to the geometric arrangement of the immersing parts (electrodes, burette tip, and stirrer). If arranged optimally,
40、 no foam is produced, not even with heavy stirring. 5.4 Combined glass pH-electrode 5.5 Solvent-resistant surface active agent -sensitive electrode (Surfactrode Resistant or Surfactrode Refill2). 5.6 Ag/AgCl- double-junction ground joint diaphragm reference electrode, inner and outer chambers filled
41、 with potassium chloride solution (4.6) 6 Sampling and preparation of the test solution 6.1 Sampling The sample shall be taken and stored in accordance with ISO 607. 6.2 Preparation of the test solutions The sample amount and the concentration of test solution shall be calculated in a way that the c
42、onsumption of the titrant solution (4.5) used for the titration of 10 ml test solution is approximately 10 ml. Weigh to the nearest 1mg, the calculated mass of the homogenized sample in a glass beaker, and dissolve it in about 100 ml water. Transfer quantitatively the sample solution into a 250 ml v
43、olumetric flask, to minimise foaming add a small quantity of ethanol (4.9). Make up to the mark with water and mix well. 7 Procedure 7.1 Standardization of the cationic surface active agent standard volumetric solution Transfer 10 ml of the sodium dodecyl sulfate standard volumetric solution (4.3) i
44、nto the titration vessel and add about 70 ml of water. Adjust with the sulfuric acid solution (4.7) until the pH value pH = 3 0,2. Add 20 ml of MIBK/ethanol-mixture (4.11) and 200 l of emulsifier (4.8) and stir the mixture intensively for 60 s in order to form a stable emulsion. 2) Surfactrode Resis
45、tant and Surfactrode Refill are trade names of apparatus 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 apparatus. Equivalent apparatus may be used if the
46、y can be shown to lead to the same results. EN 14480:2004 (E) 7 Carry out the titration with the cationic surface active agent standard volumetric solution (4.5) under intensive stirring (5.3). Record the reagent consumption, V, at the inflection point of the titration curve (see Figure B.1). NOTE E
47、xamples for instrument settings are given in Annex A. Calculate the factor, f , of the cationic surface active agent standard volumetric solution (4.5) by the equation (2): baicVVcf=1(2) where fiis the determined factor of cationic surface active agent standard volumetric solution (4.5); cais the co
48、ncentration of the anionic surface active agent standard volumetric solution expressed in millimoles per millilitre (4.3); cbis the concentration of the cationic surface active agent standard volumetric solution expressed in millimoles per millilitre (here 0,005 mmol/ml); V1is the volume of anionic
49、surface active agent standard volumetric solution used, in millilitres (here : 10 ml); V is the consumption of cationic surface active agent standard volumetric solution (4.5), in millilitres. Repeat the determination at least three times and calculate from the factors fithe average factor f. 7.2 Determination of the anionic surface active agents Transfer 10 ml of the test solution (see 6.2) into the titration vessel and add 70 ml water. Carry out the determination as specified in 7.1. The a
