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1、International Standard 457 0 INTERNATIONAL ORGANIZATION FOR STANDARDIZATlON*MEKL1YHAPOflHAR OPAHH3AUMR fl0 CTAHAPTH3AUMHRGANlSATlON INTERNATIONALE DE NORMALISATION Soaps - Determination of chloride content - Titrimetric method Savons - Dosage des chlorures - M this method is applicable to soaps havi
2、ng a chloride content, expressed as sodium chloride, equal to or greater than 0,l % h/m). ) 2 Principle Determination of the chloride content by argentimetric titration after decomposition of a test portion and separation of fatty acids by filtration. 3 Reagents During the analysis, use only reagent
3、s of recognized analytical reagent quality and only distilled water or water of at least equivalent purity. 3.1 Nitric acid, Q approximately 1.42 g/ml, about 70 to 80 % (m/m) solution, which has been boiled until colourless. 3.2 Ammonium iron(llll sulfate, about 10 % (m/m) solu- tion. 3.3 Ammonium t
4、hiocyanate, standard volumetric solu- tion, c(NH4SCN) = 0,l mol/l. 3.4 Silver nitrate, standard volumetric solution, c(AgNOs) = 0,l mol/l. 4 Apparatus Ordinary laboratory apparatus, and in particular : 4.1 Beaker, capacity 100 ml, tall form, complying with the requirements of IS0 3819. 4.2 One-mark
5、volumetric flask, capacity 200 ml, comply- ing with the requirements of IS0 1042. 4.3 Boiling water bath. 5 Sampling Sampling of soaps will form the object of a future International Standard. 6 Procedure 6.1 Test portion Weigh, to the nearest 0,Ol g, approximately 5 g of the laboratory sample into t
6、he beaker (4.1). 6.2 Determination Dissolve the test portion (6. I) in 50 ml of hot water. Transfer the solution quantitatively to the one-mark volumetric flask (4.2). effecting this by washing with small portions of water. Add 5 ml of the nitric acid solution (3.1). and immediately add 25.0 ml of t
7、he silver nitrate solution (3.4). Place the flask on the 1) The potentiometric method specified in IS0 4323 can be used for products having a chloride content, expressed as sodium chloride, higher or lower than 0,l % (m/m). 1 Copyright International Organization for Standardization Provided by IHS u
8、nder license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/25/2007 20:13:59 MDTNo reproduction or networking permitted without license from IHS -,-,- IS0 457-1983 (E) boiling water bath (4.3) until the fatty acids are completely separated and the silver chloride formed h
9、as collected in a mass. Cool the one-mark volumetric flask and contents to room temperature and dilute to the mark with water. Mix by shaking and filter through a dry, fluted filter paper. Discard the first 10 ml, and then collect at least 110 ml, of the filtrate. Transfer, using a pipette, 100,O ml
10、 to a conical flask, add 2 to 3 ml of the ammonium ironfIll) sulfate solution (3.2) and titrate with the standard volumetric ammonium thiocyanate solution (3.31, shaking the conical flask vigorously, until the appearance of a permanent reddish-brown coloration. 7 Expression of results 7.1 Method of
11、calculation The chloride content of the soap, expressed as a percentage by mass of sodium chloride (NaCI), is given by the formula 0,056 5 x (25 c, - 2 Vc2) x = m and, as a percentage by mass of potassium chloride (KCI), by the formula 100 0,074 6 x (25 cl - 2 Vc2) x - m c2 is the actual concentrati
12、on, expressed in moles of NH,SCN per litre, of the ammonium thiocyanate solution (3.3); 0,056 5 is the mass, in grams, of sodium chloride cor- responding to I,00 ml of the silver nitrate solution, c(AgNOs) = 1,000 mol/l; 0,074 6 is the mass, in grams, of potassium chloride cor- responding to I,00 ml
13、 of the silver nitrate solution, c(AgNOs) = 1,000 mol/l. 7.2 Reproducibility The difference between results obtained on the same sample in two different laboratories should not differ by more than 0,05 % from the value of the percentage by mass of chlorides found, expressed either as sodium chloride
14、 or as potassium chloride. 8 Test report The test report shall include the following information : a) all information necessary for the complete identification of the sample; b) the reference of the method used (reference to this International Standard); where m is the mass, in grams, of the test po
15、rtion (6.1); V is the volume, in millilitres, of the standard volumetric ammonium thiocyanate solution (3.3) used; cl is the actual concentration, expressed in moles of AgNOs per litre, of the silver nitrate solution (3.4); c) the results and the method of expression used; d) the test conditions; e)
16、 any details not specified in this International Standard, or regarded as optional, as well as any incidents likely to have affected the results. 2 Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/25/2007 20:13:59 MDTNo reproduction or networking permitted without license from IHS -,-,-