(ISO 456 NTERNATIONAL STANDARD INTERNATIONAL ORGANIZATION FOR STANDARDIZATION·MEKAYHAPOAHAH OPTAHM3ALIMA HIO CTAHIAPTM3ALIMM.ORGANISATION INTERNATIONALE DE NORMALISATION Surface active agents -- Analysis of soaps Determination of free caustic alkali First edition - 1973-03-01 NA12热3 UDC 661.185 Ref. No. ISO 456-1973 (E) (3) ISO 456-1973 ( Descriptors : surfactants, soaps, chemical analysis, determination of content, alkalies. Price based on 3 pages Copyright International Organizationfor Standardization tted without license from IHS Not for Resale FOREWORD IsO (the International Organization for Standardization) is a worldwide federation of national standards institutes (IsO Member Bodies). The work of developing International Standards is carried out through isO Technical Committees. Every Member Body interested in a subject for which a Technical Committee has been set up has the right to be represented on that Committee. International organizations, Draft International Standards adopted by the Technical Committees are circulated to the Member Bodies for approval before their acceptance as International Standards by the iSO Council. Prior to 1972, the results of the work of the Technical Committees were published as IsO Recommendations; these documents are now in the process of being transformed into International Standards. As part of this process, International Standard ISO 456 replaces ISO Recommendation R 456-1965 drawn up by Technical Committee ISO/TC 91, Surface active agents. The Member Bodies of the following countries approved the Recommendation : Hungary Argentina Poland Austria Italy Portugal Canada Japan Romania Korea, Rep. of Spain Chile Switzerland Colombia Morocco Czechoslovakia Netherlands United Kingdom France New Zealand Yugoslavia Germany Norway Body of the following country expressed disapproval of the TheMember Recommendation on technical grounds : India @ International Organization for Standardization, 1973 : 'Printed in Switzerland Copyright International Organization for Standardization e from IHS Not for Resale INTERNATIONAL STANDARD ISO 456-1973 (E) Surface active agents -- Analysis of soaps Determination of free caustic alkali 0 INTRODUCTiON 4 METHOD A (Ethanol method) As soaps usually contain a small amount of unsaponified 4.1 Principle neutral fat, there is no perfect procedure for determining free caustic alkali because, when the sample of soap is The soap is dissolved in neutralized ethanol, and the free dissolved, a neutral fat is more or less saponified by any caustic alkali is titrated with an ethanolic solution of free caustic alkali that is present. hydrochloric acid. Both methods described in this Internationa! Standard are therefore of a conventiona! nature. 4.2 Reagents Conventionally, free caustic alkali is expressed as The water used shall be distilled water or water of at least equivalent purity. sodium hydroxide (NaOH) for sodium soaps and The reagents shall have the following properties : potassium hydroxide (KOH) for potassium soaps. 4.2.1 Ethanol, absolute, P2o = 0,792 g/ml. 1 SCOPE 4.2.2 Potassium hydroxide, ethanolic solution, approximately 0,1 N. This International Standard specifies two methods of determining free caustic alkali in commercial soaps, 4.2.3 Hydrochloric acid, standard ethanolic solution, excluding compounded products : approximately 0,1 N. Method A, ethanol method; 4.2.4 Phenolphthalein solution, 1 g in 100 ml of 95 % Method B, barium chloride method. (V/V) ethanol. 4.3 Apparatus 2 FIELD OF APPLICATION Ordinary iaboratory apparatus, and in particular 2.1 Method A (ethanol method) should be applied only to sodium soaps of ordinary quality, as the presence of certain 4.3.1 Flask of approximately 500 ml capacity, that can be additives brings in sources of error. It is not applicable to fitted to a reflux condenser. potassium soaps, because of the solubility of potassium carbonate in ethanol. 4.3.2 Reflux condenser. 2.2 Method B (barium chloride method) should be