1、BRITISH STANDARD BS 1715-2.1: 1989 ISO 685:1975 Analysis of soaps Part 2: Quantitative test methods Section 2.1 Method for determination of total alkali content and total fatty matter content ISO title: Analysis of soaps Determination of total alkali content and total fatty matter content UDC 661.18
2、:661.187.2:543BS1715-2.1:1989 This British Standard, having been prepared under the directionof the Chemicals Standards Policy Committee, was published under the authority ofthe Board of BSI and comes into effect on 31July1989 BSI 08-1999 The following BSI references relate to the work on this stand
3、ard: Committee reference CIC/34 Draft for comment 88/53280 DC ISBN 0 580 17287 2 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
4、were represented: Chemical Industries Association Consumer Policy 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 Colouri
5、sts Amendments issued since publication Amd. No. Date of issue CommentsBS1715-2.1:1989 BSI 08-1999 i Contents Page Committees responsible Inside front cover National foreword ii 1 Scope and field of application 1 2 References 1 3 Definitions 1 4 Principle 1 5 Reagents 1 6 Apparatus 1 7 Sampling 1 8
6、Procedure 1 9 Expression of results 2 10 Test report 3 Publication referred to Inside back coverBS1715-2.1:1989 ii BSI 08-1999 National foreword This Section of BS 1715 has been prepared under the direction of the Chemicals Standards Policy Committee. It is identical with ISO685:1975 “Analysis of so
7、aps Determination of total alkali content and total fatty matter content” published by the International Organization for Standardization (ISO). This method supersedes the methods for determination of total fatty matter and determination of total alkali given in BS1715:1963, which are deleted by ame
8、ndment. Terminology and conventions. The text of the International Standard has been approved as suitable for publication as a British Standard without deviation. Some terminology and certain conventions are not identical with those used in British Standards; attention is drawn especially to the fol
9、lowing. 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 symbol “l” has been used to denote litre (and in its submultiples). In British Standards it is current practice to use the symbol “L”. Where
10、ver 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 and clause7) is not yet published. Relevant information on sampling is included in BS1715 “Analysis of soaps”, Part1:19
11、89 “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 BS3978 “Specification for water for laboratory use” is suitable. With reference to5.4, the sulphuric acid or
12、 hydrochloric acid standard volumetric solution, expressed as an amount-of substance concentration, is c(“H 2SO 4 )=1mol/L or c(HCl)=1mol/L. With reference to5.5 and5.6, the sodium hydroxide and potassium hydroxide standard volumetric solutions, expressed as amount-of-substance concentrations, are c
13、(NaOH)=1mol/L andc(KOH)=1mol/L, respectively. In the definitions of T 0and T 1in9.1.1, and T in9.2.1, “normality” should be read as “amount-of-substance concentration (mol/L)”. For the purposes of5.3 the ethanol may be replaced by industrial methylated spirits complying with BS3591 “Specification fo
14、r 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 permissible to use duty-free ethanol, received under the provisions of the Alcoholic Liquors
15、Duties Act1972, Section10, for purposes for which industrial methylated spirits is an acceptable alternative. 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 should indicate that the method of test
16、 used is in accordance with BS1715-2.1. Cross-reference International Standard Corresponding British Standard ISO 684:1974 BS 1715 Analysis of soaps Section 2.2:1989 Method for determination of total free alkali content (Identical)BS1715-2.1:1989 BSI 08-1999 iii A British Standard does not purport t
17、o 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 immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover,
18、 pages i to iv, pages1to 4, 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 the amendment table on the inside front cover.iv blankBS1715-2.1:1989 BSI 08-1999 1 1 Scope and field of applicat
19、ion This International Standard specifies a method for the simultaneous determination of the total alkali 1) ) content and the total fatty matter content of soaps, excluding compounded products. This method for the determination of total alkali is not applicable to coloured soaps if the colour inter
20、feres with the methyl orange end-point. 2 References ISO 684, Analysis of soaps Determination of total free alkali. ISO ., Soaps Sampling 2) . 3 Definitions For the purposes of this International Standard, the following definitions apply: total alkali the sum of the alkali bases combined as soap wit
21、h fatty and rosin acids, as well as those corresponding to free alkali metal hydroxides or carbonates and to any silicates present which will be titrated under the test conditions the results are expressed as a percentage by mass of either sodium hydroxide (NaOH) or of potassium hydroxide (KOH), acc
22、ording to whether sodium or potassium soaps are concerned total fatty matter the water-insoluble fatty material obtained by decomposing the soap with a mineral acid under the conditions specified. This term includes unsaponifiable matter, glycerides and any rosin acids contained in the soap, in addi
23、tion to the fatty acids 4 Principle Decomposition of the soap by a known volume of standard volumetric mineral acid solution, extraction and separation of the liberated fatty matter with light petroleum and determination of the total alkali content by titration of the excess of acid contained in the
24、 aqueous phase with a standard volumetric sodium hydroxide solution. After evaporation of the light petroleum from the extract, dissolution of the residue in ethanol and neutralization of the fatty acids with a standard volumetric potassium hydroxide solution. Evaporation of the ethanol and weighing
25、 of the soap formed to determine the total fatty matter content. 5 Reagents During the analysis, use only reagents of recognized analytical reagent grade and only distilled water or water of equivalent purity. 5.1 Acetone 5.2 Light petroleum, boiling range between40and60 C. 5.3 Ethanol, 95 % (V/V) s
26、olution, neutralized to the phenolphthalein solution (5.8). 5.4 Sulphuric acid or hydrochloric acid, approximately1N standard volumetric solution 5.5 Sodium hydroxide, approximately1N standard volumetric solution, standardized using the methyl orange solution (5.7) as indicator. 5.6 Potassium hydrox
27、ide, approximately1N standard volumetric solution in ethanol (5.3). 5.7 Methyl orange,2g/l solution. 5.8 Phenolphthalein, 10g/l solution in ethanol (5.3). 6 Apparatus Ordinary laboratory apparatus and 6.1 Beaker, capacity250ml, squat form, complying with ISO3819. 6.2 Separating funnels, capacity500m
28、l, or 6.3 Extraction cylinder, capacity250ml, diameter39mm and height355mm, fitted with a ground glass stopper. 6.4 Water bath 6.5 Oven, capable of being controlled at103 2 C. 7 Sampling The laboratory sample of soap shall be prepared and stored in accordance with the instructions given in ISO. 8 Pr
29、ocedure Carry out two determinations on the same sample. 8.1 Test portion Weigh, to the nearest0,001g, about5g of the laboratory sample into the beaker (6.1). 8.2 Determination Dissolve the test portion (8.1) in about100ml of hot water. Pour the solution into one of the separating funnels(6.2) or in
30、to the extraction cylinder (6.3) and wash the beaker with small quantities of water, adding the washings to the separating funnel or to the extraction cylinder. 1) See also ISO 684. 2) In preparation.BS1715-2.1:1989 2 BSI 08-1999 Add a few drops of the methyl orange solution (5.7) and then, from a b
31、urette, add, while vigorously shaking the separating funnel or the extraction cylinder, an accurately measured known volume of the sulphuric acid or hydrochloric acid solution (5.4) until there is an excess of about5ml. Cool the contents of the separating funnel or of the extraction cylinder to abou
32、t25 C and add 100 ml of the light petroleum (5.2). Insert the stopper and gently invert the separating funnel or the extraction cylinder, whilst maintaining a hold on the stopper. Open the stopcock of the separating funnel or the stopper of the extraction cylinder gradually to release any pressure,
33、then close, gently shake and again release the pressure. Repeat the shaking until the aqueous layer has become clear, and then allow to stand. a) In the case of use of separating funnels Run off the aqueous layer into a second separating funnel (6.2) and extract with50ml of the light petroleum (5.2)
34、. Repeat the process, collect the aqueous layer in a conical flask and combine the three light petroleum extracts in the first separating funnel. b) In the case of use of an extraction cylinder Using a siphon, draw off the light petroleum layer as completely as possible into a separating funnel (6.2
35、). Repeat the extraction twice with50ml of the light petroleum (5.2), combine the three light petroleum extracts in the separating funnel, transfer the aqueous layer as completely as possible to a conical flask and wash the extraction cylinder with small quantities of water, adding the washings to t
36、he conical flask. Wash the light petroleum extract by shaking with water (about25ml) until the washings are neutral to the methyl orange solution (5.7). Usually three washings are sufficient. NOTEAllow each wash to stand for at least5min or such a time as is required to give a clear line of demarcat
37、ion between the layers, before running off the aqueous layer. After the final washing has been run off, impart a swirling motion to the contents of the separating funnel by rotating it sharply, but without inverting it, to remove any water droplets adhering to the sides. Allow to stand for at least
38、5 min and run off any separated water. Collect the washings of the light petroleum extract quantitatively in the conical flask already containing the aqueous layer. 8.2.1 Determination of total alkali content Titrate the mixed acid aqueous layer and washings with the sodium hydroxide solution (5.5)
39、using the methyl orange solution (5.7) as indicator. 8.2.2 Determination of total fatty matter content Carefully transfer the washed light petroleum solution to a weighed, flat-bottomed flask, filtering if necessary through a dry filter paper. Wash the separating funnel with two or three small quant
40、ities of the light petroleum and filter the washings into the flask, taking precautions to prevent evaporation of the light petroleum during the filtration. Thoroughly wash the filter with the light petroleum, collecting the washings in the flask. Evaporate off nearly all the light petroleum on the
41、water bath (6.4), taking all necessary precautions, and under a slow stream of cold dry nitrogen or air. Dissolve the residue in20ml of the ethanol (5.3), add a few drops of the phenolphthalein solution (5.8) and titrate with the ethanolic potassium hydroxide solution (5.6) to a faint permanent pink
42、 colour. Note the volume used. Evaporate the ethanolic solution on the water bath(6.4). When the evaporation is near completion, rotate the flask in order to distribute the potassium soap in a thin layer on the sides and bottom of the vessel. Carry out a preliminary drying of the potassium soap by a
43、dding acetone (5.1) and evaporating off the acetone on the water bath under a slow stream of cold dry nitrogen or air. Then heat to constant mass in the oven (6.5), controlled at103 2 C, i.e. until the difference in mass after heating for an additional15min does not exceed3mg. Cool in a desiccator a
44、nd weigh. 9 Expression of results 9.1 Total alkali content 9.1.1 Method of calculation and formulae The total alkali content is given, as a percentage by mass, by the formulae: a) expressed as sodium hydroxide (NaOH) for sodium soaps, and b) expressed as potassium hydroxide (KOH) for potassium soaps
45、, and where m is the mass, in grams, of the test portion (8.1); V 0is the volume, in millilitres, of the standard volumetric acid solution (5.4) used; V 1is the volume, in millilitres, of the standard volumetric sodium hydroxide solution (5.5) used; 0,040V 0 T 0 V 1 T 1 () 100 m - 0,056V 0 T 0 V 1 T
46、 1 () 100 m - BS1715-2.1:1989 BSI 08-1999 3 T 0is the exact normality of the standard volumetric acid solution (5.4); T 1is the exact normality of the standard volumetric sodium hydroxide solution (5.5). The total alkali content may also be expressed in milliequivalents per gram by the formula: Take
47、 as the result the arithmetic mean of the duplicate determinations. 9.1.2 Reproducibility The difference between the results obtained on the same sample in two different laboratories should not differ by more than0,2% from the value of the percentage by mass of total alkali found, expressed either a
48、s sodium hydroxide or as potassium hydroxide. 9.2 Total fatty matter content 9.2.1 Method of calculation and formula The total fatty matter content is given, as a percentage by mass, by the formula: where m 0is the mass, in grams of the test portion (8.1); m 1is the mass, in grams, of the dried pota
49、ssium soap; V is the volume, in millilitres, of the standard volumetric ethanolic potassium hydroxide solution (5.6) used for the neutralization; T is the exact normality of the standard volumetric ethanolic potassium hydroxide solution (5.6) used. Take as the result the arithmetic mean of the duplicate determinations, rounding the result to the nearest0,1%. 9.2.2 Reproducibility The difference between the results obtained on the same sample in two different laboratories should not differ by more than0,2% from the value of the p
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