1、BRITISH STANDARD BS 1715-2.2: 1989 ISO 684:1974 Analysis of soaps Part 2: Quantitative test methods Section 2.2 Method for determination of total free alkali content ISO title: Analysis of soaps Determination of total free alkali UDC 661.18:661.3:543BS1715-2.2:1989 This British Standard, having been
2、 prepared under the directionof the Chemicals Standards Policy Committee, waspublished under the authorityof the Board of BSI andcomes into effect on 31July1989 BSI 08-1999 The following BSI references relate to the work on this standard: Committee reference CIC/34 Draft for comment 88/53279 DC ISBN
3、 0 580 17288 0 Committees responsible for this British Standard The preparation of this British Standard was entrusted by the Chemicals Standards Policy Committee (CIC/-) to Technical Committee CIC/34, upon which the following bodies were represented: Chemical Industries Association Consumer Policy
4、Committee of BSI Department of the Environment Department of Trade and Industry (Laboratory of the Government Chemist) Ministry of Defence Royal Society of Chemistry Soap and Detergent Industry Association Society of Dyers and Colourists Amendments issued since publication Amd. No. Date of issue Com
5、mentsBS1715-2.2:1989 BSI 08-1999 i Contents Page Committees responsible Inside front cover National foreword ii 1 Scope 1 2 References 1 3 Definition 1 4 Principle 1 5 Reagents 1 6 Apparatus 1 7 Sampling 1 8 Procedure 1 9 Expression of results 1 10 Test report 2 Publications referred to Inside back
6、coverBS1715-2.2:1989 ii BSI 08-1999 National foreword This Section of BS1715 has been prepared under the direction of the Chemicals Standards Policy Committee. It is identical with ISO684:1974 “Analysis of soaps Determination of total free alkali” published by the International Organization for Stan
7、dardization (ISO). This method supersedes the method for determination of total free alkali given in BS1715:1963, which is deleted by amendment. Terminology and conventions. The text of the International Standard has been approved as suitable for publication as a British Standard without deviation.
8、Some terminology and certain conventions are not identical with those used in British Standards; attention is drawn especially to the following. The comma has been used as a decimal marker. In British Standards it is current practice to use a full point on the baseline as the decimal marker. The sym
9、bol “ml” has been used to denote millilitre. In British Standards it is current practice to use the symbol “mL”. Wherever the words “International Standard” appear, referring to this standard, they should be read as “Section of BS1715”. The International Standard for sampling of soaps (see clause2 a
10、nd clause7) is not yet published. Relevant information is included in BS1715 “Analysis of soaps”, Part 1:1989 “General introduction, sampling, and test for presence of synthetic anionic-active surface active agents”. Additional information. With reference to clause5, water complying with grade3 of B
11、S3978 “Specification for water for laboratory use” is suitable. With reference to5.2, the sulphuric acid standard volumetric solution, expressed as an amount-of-substance concentration, is c(“H 2 SO 4 ) = 1mol/L. With reference to5.3, the potassium hydroxide standard volumetric solution, expressed a
12、s an amount-of-substance concentration, is c(KOH) =0.1mol/L. In the definitions of T 0and T 1in9.1, “normality” should be read as “amount-of-substance concentration (mol/L)”. In the penultimate paragraph of9.1, “milliequivalents” should be read as “millimoles”. For the purposes of5.1 the ethanol may
13、 be replaced by industrial methylated spirits complying with BS3591 “Specification for industrial methylated spirits” of appropriate strength. It should be noted that the use of industrial methylated spirits is governed by The Methylated Spirits Regulations, 1983 (S.I.1983 No.252). It is not permiss
14、ible to use duty-free ethanol, received under the provisions of the Alcoholic Liquors Duties Act1972, Section10, for purposes for which industrial methylated spirits is an acceptable alternative. Cross-reference International Standard Corresponding British Standard ISO 685:1975 BS 1715 Analysis of s
15、oaps Section 2.1:1989 Method for determination of total alkali content and total fatty matter content (Identical)BS1715-2.2:1989 BSI 08-1999 iii This Section describes a method of test only, and should not be used or quoted as a specification defining limits of purity. Reference to this Section shou
16、ld indicate that the method of test used is in accordance with BS1715-2.2. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer
17、 immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i to iv, pages1and 2, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in
18、the amendment table on the inside front cover.iv blankBS1715-2.2:1989 BSI 08-1999 1 1 Scope and field of application This International Standard specifies a method for the determination of the total free alkali content of commercial soaps, excluding compounded products 1) . The method is not applica
19、ble if the soap contains additives (alkali silicates, etc.) which can be decomposed by sulphuric acid by the procedure specified. The method is also not applicable to coloured soaps if the colour interferes with the phenolphthalein end point. 2 References ISO 685, Analysis of soaps Determination of
20、total alkali 2) . ISO . . ., Soaps Sampling 3) . 3 Definition For the purpose of this International Standard, the following definition applies: 3.1 total free alkali the sum of the free caustic alkali and the free carbonate alkali contents the results are generally expressed as a percentage by mass
21、as either sodium hydroxide (NaOH) for sodium soaps or potassium hydroxide (KOH) for potassium soaps they may also be expressed in milliequivalents per gram 4 Principle Dissolution of the soap in an ethanolic solution, neutralization of the free alkali with a known excess of sulphuric acid solution a
22、nd back titration of the excess acid with ethanolic potassium hydroxide solution. 5 Reagents During the analysis, use only reagents of recognized analytical reagent grade and only distilled water or water of equivalent purity. 5.1 Ethanol, 95% (V/V) solution, free from carbon dioxide. Reflux this so
23、lution for5min, cool to ambient temperature and neutralize with the ethanolic potassium hydroxide solution (5.3) in the presence of4 drops of the phenolphthalein solution (5.4) per200ml of ethanol. 5.2 Sulphuric acid, approximately N standard volumetric solution. 5.3 Potassium hydroxide, approximate
24、ly0,1 N ethanolic standard volumetric solution. 5.4 Phenolphthalein, solution of1g per100ml in95% (V/V) ethanol. 6 Apparatus Ordinary laboratory apparatus and 6.1 Conical flask, capacity250ml, with a conical ground glass joint. 6.2 Reflux condenser, water-cooled, with a conical ground glass joint at
25、 the bottom. 7 Sampling Laboratory samples shall be prepared and stored according to the procedures specified in ISO. 8 Procedure 8.1 Test portion Weigh, to the nearest0,001g, about5g of the laboratory sample into the conical flask (6.1). 8.2 Determination Add100ml of the ethanol solution (5.1) to t
26、he test portion (8.1). Fit the conical flask (6.1) to the reflux condenser(6.2). Gently heat until the soap is completely dissolved, then add exactly3,0ml 4)of the sulphuric acid solution (5.2) and boil gently for at least10min. Allow to cool to ambient temperature. Titrate with the ethanolic potass
27、ium hydroxide solution (5.3) in the presence of the indicator (5.4). Carry out two determinations on the same sample. 9 Expression of results 9.1 Method of calculation and formulae The total free alkali content, expressed as a percentage by mass of sodium hydroxide (NaOH) in the case of sodium soaps
28、, is given by the formula: 1) See also ISO685. 2) At present at the stage of draft. (Revision of ISO/R 685.) 3) In preparation. 4) This volume may be increased for certain soaps with high total free alkali contents. 0,040 V 0 T 0 V 1 T 1 m - 100 BS1715-2.2:1989 2 BSI 08-1999 The total free alkali co
29、ntent, expressed as a percentage by mass of potassium hydroxide (KOH) in the case of potassium soaps, is given by the formula: where The total free alkali may also be expressed in milliequivalents per gram by the formula: Take as the result the arithmetic mean of the duplicate determinations. 9.2 Re
30、producibility The results obtained on the same sample in two different laboratories, expressed either as sodium hydroxide (NaOH) or as potassium hydroxide (KOH), shall not differ by more than0,05%. 10 Test report The test report shall include the following particulars: a) all information necessary f
31、or the complete identification of the sample; b) the reference to method used, reference being made to this International Standard; c) the results obtained and the method of expression used; d) the test conditions; e) any operational details not specified in this International Standard, or regarded
32、as optional, as well as all incidents likely to have affected the results. m is the mass, in grams, of the test portion (8.1); V 0 is the volume, in millilitres, of the sulphuric acid solution (5.2) used in the determination; V 1 is the volume, in millilitres, of the potassium hydroxide solution (5.
33、3) used in the titration; T 0 is the exact normality of the sulphuric acid solution (5.2); T 1 is the exact normality of the potassium hydroxide solution (5.3). 0,056 V 0 T 0 V 1 T 1 m - 100 V 0 T 0 V 1 T 1 m -BS1715-2.2:1989 BSI 08-1999 Publications referred to See national foreword.BS 1715-2.2: 19
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