Surface active agents - Determination of anionic surface active agents - Potentiometric two-phase titration method

This document specifies a method for the 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 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 toxicologically critical chloroform.

Grenzflächenaktive Stoffe - Bestimmung von anionischen grenzflächenaktiven Stoffen - Potentiometrische Zweiphasen-Titration

Dieses Dokument legt ein Verfahren zur Bestimmung des Gehaltes an anionischen grenzflächenaktiven Stoffen in Rohstoffen als die Menge der anionischen grenzflächenaktiven Stoffe, angegeben in Millimol je 100 g des Produktes, fest.
ANMERKUNG 1   Die Anwendbarkeit auf andere Produkte sollte in jedem einzelnen Fall geprüft werden.
ANMERKUNG 2   Im Vergleich zur üblichen Zweiphasen-Titration mit visueller Endpunktbestimmung (siehe ISO 2271) bietet die potentiometrische Titration den Vorteil der Automatisierung, vom Analytiker abhängige Abweichungen bei der Erkennung des Äquivalenzpunktes können vernachlässigt werden, und ein nicht kritisches Lösemittel ersetzt das toxikologisch kritische Chloroform.

Agents de surface - Détermination des agents de surface anioniques - Méthode potentiométrique de titrage dans deux phases

Le présent document spécifie une méthode de détermination de la teneur en agents de surface anioniques dans les matieres premieres, définies comme étant la quantité d'agents de surface anioniques exprimée en millimoles pour 100 g de produit.
NOTE 1   Il convient que l'applicabilité pour des produits différents de ceux soumis a essai soit vérifiée pour chaque cas particulier.
NOTE 2   En comparaison avec le titrage classique en laboratoire dans deux phases avec détermination visuelle du point de virage (voir ISO 2271), le titrage potentiométrique offre l'avantage d'etre automatisé, les écarts imputables a l'opérateur dans l'identification du point d'équivalence pouvant ainsi etre négligés et de remplacer le chloroforme, critique sur le plan toxicologique, par un solvant non critique.

Površinsko aktivne snovi – Določevanje anionskih površinsko aktivnih snovi – Potenciometrična dvofazna titracijska metoda

General Information

Status
Published
Publication Date
30-Sep-2004
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
01-Oct-2004
Due Date
01-Oct-2004
Completion Date
01-Oct-2004

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2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Grenzflächenaktive Stoffe - Bestimmung von anionischen grenzflächenaktiven Stoffen - Potentiometrische Zweiphasen-TitrationAgents de surface - Détermination des agents de surface anioniques - Méthode potentiométrique de titrage dans deux phasesSurface active agents - Determination of anionic surface active agents - Potentiometric two-phase titration method71.100.40Površinsko aktivna sredstvaSurface active agentsICS:Ta slovenski standard je istoveten z:EN 14480:2004SIST EN 14480:2004en01-oktober-2004SIST EN 14480:2004SLOVENSKI
STANDARD



SIST EN 14480:2004



EUROPEAN STANDARDNORME EUROPÉENNEEUROPÄISCHE NORMEN 14480September 2004ICS 71.100.40English versionSurface active agents - Determination of anionic surface activeagents - Potentiometric two-phase titration methodAgents de surface - Détermination des agents de surfaceanioniques - Méthode potentiométrique de titrage dansdeux phasesGrenzflächenaktive Stoffe - Bestimmung von anionischengrenzflächenaktiven Stoffen - PotentiometrischeZweiphasen-TitrationThis European 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 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 responsibility 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, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia,Slovenia, Spain, Sweden, Switzerland and United Kingdom.EUROPEAN COMMITTEE FOR STANDARDIZATIONCOMITÉ EUROPÉEN DE NORMALISATIONEUROPÄISCHES KOMITEE FÜR NORMUNGManagement Centre: rue de Stassart, 36
B-1050 Brussels© 2004 CENAll rights of exploitation in any form and by any means reservedworldwide for CEN national Members.Ref. No. EN 14480:2004: ESIST EN 14480:2004



EN 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 expression 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
SIST EN 14480:2004



EN 14480:2004 (E) 3 Foreword 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 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, 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. SIST EN 14480:2004



EN 14480:2004 (E) 4 1 Scope This document specifies a method for the 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 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 toxicologically 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) applies. 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 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 agent 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 active 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). 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 and 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, C12H25OSO3Na, w(C12H25OSO3Na) ≥ 99 % as determined following the method prEN 14670 SIST EN 14480:2004



EN 14480:2004 (E) 5 4.3 Anionic surface active agent standard volumetric solution, ca(C12 H25OSO3Na) = 0,005 mol/l
Weigh 1,455 g of sodium dodecyl sulfate (sodium lauryl sulfate) (4.2) with a known active content to the nearest 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 millilitre 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 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 = 0,005 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. 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 titration 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 preventing 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: 108-11.2), 4-methyl-2-pentanol, w (C6 H12O) ≥ 99 %. 4.11 MIBK/ethanol-mixture Measure 500 ml MIBK (4.10) and 500 ml ethanol 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 product. Equivalent product may be used if it can be shown to lead to the same results. SIST EN 14480:2004



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 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 simultaneous 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, 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 with potassium chloride solution
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