1、BRITISH STANDARD BS3762-3.9: 1986 Analysis of formulated detergents Part3: Quantitative test methods Section3.9 Method for determination of soap content NOTEIt is recommended that this Section be read in conjunction with the information in the “General Introduction”, published separately as BS3762-0
2、. UDC 661.185:543.24:543.856.062BS3762-3.9:1986 This BritishStandard, having been prepared under the directionof the Chemicals Standards Committee, was published under the authorityofthe Board of BSI andcomes intoeffect on 28 November 1986 BSI 12-1999 The committees responsible for this BritishStand
3、ard are showninPart0. The following BSI references relate to the work on this standard: Committee reference CIC/34 Draft for comment85/55068DC ISBN 0 580 15507 2 Foreword This Section of BS3762 has been prepared under the direction of the Chemicals Standards Committee and supersedes method B12 of BS
4、3762:1964, which is being deleted by amendment. This standard describes a method of test only and should not be referred to as a specification defining limits of purity. Reference to the standard should indicate that the method of test used is in conformity with BS3762-3.9. A British Standard does n
5、ot 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 immunity from legal obligations. Summary of pages This document comprises a front cover, an inside
6、front cover, pagesi andii, pages1 and 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 the amendment table on the inside front cover. Amendments issued since publication Amd. No. Date of
7、issue CommentsBS3762-3.9:1986 BSI 12-1999 i Contents Page Foreword Inside front cover 1 Scope 1 2 Principle 1 3 Reagents 1 4 Apparatus 1 5 Procedure 1 6 Expression of results 1 7 Precision 2 8 Test report 2 Publications referred to Inside back coverii blankBS3762-3.9:1986 BSI 12-1999 1 1 Scope This
8、Section of BS3762 describes a method for the determination of the soap content of formulated detergents. The mean relative molecular mass of the soap has to be known. NOTEThe titles of the publications referred to in this Section are listed on the inside back cover. 2 Principle An acidified solution
9、 of the detergent is extracted with light petroleum. The extract is concentrated by evaporation and titrated with sodium hydroxide standard volumetric solution. 3 Reagents The reagents shall be of a recognized analytical grade. Water complying with BS3978 shall be used throughout. 3.1 Ethanol NOTEFo
10、r the purposes of 3.1 the ethanol may be replaced by industrial methylated spirits complying with BS3591, or such spirits diluted as required. 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
11、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. 3.2 Light petroleum, boiling range40 C to60 C. 3.3 Sulphuric acid solution, c(H 2 SO 4 )=5mol/L approxim
12、ately. 3.4 Sodium hydroxide standard volumetric solution, c(NaOH)=0.100mol/L. 3.5 Bromophenol blue indicator solution 3.6 Phenolphthalein indicator solution,5g/L in50% ethanol solution. 3.7 Sodium chloride 4 Apparatus Ordinary laboratory apparatus and the following are required. 4.1 Separating funne
13、ls, of250mL capacity. 4.2 Flask, of250mL capacity, fitted with a24/29 ground glass joint (seeBS572). 4.3 Distillation apparatus, to fit4.2. 5 Procedure 5.1 Test portion Weigh, to the nearest0.01g, approximately5g of synthetic detergent or approximately3g of formulated soap-based powder into a150mL b
14、eaker. 5.2 Determination 5.2.1 Add to the test portion50mL of water, heat to between40 C and50 C, stir and add50mL of the ethanol(3.1) and a few drops of the bromophenol blue indicator solution(3.5). 5.2.2 Add the sulphuric acid solution(3.3) drop by drop until the solution is acid. Transfer the sol
15、ution to a separating funnel(4.1). Wash the beaker with50mL of the light petroleum(3.2) and transfer the washings to the separating funnel. 5.2.3 Stopper the separating funnel(4.1) and shake vigorously, occasionally inverting the separating funnel and opening the stopcock to release the pressure. Al
16、low the layers to separate. NOTEIf difficulty is experienced in obtaining a satisfactory separation of the layers, the addition of small amounts of sodium chloride (3.7) or warming of the mixture may assist. 5.2.4 Remove the stopper and run the lower layer into a second separating funnel(4.1). To th
17、is second separating funnel add50mL of the light petroleum(3.2). 5.2.5 Repeat the procedure in5.2.3, then remove the stopper, run the lower layer into the original beaker and transfer the petroleum layer to the separating funnel containing the first extract. 5.2.6 Extract the aqueous layer with a fu
18、rther50mL of the light petroleum(3.2) using the second separating funnel and transfer the petroleum layer to the separating funnel containing the first two extracts. Wash once with50mL of water and discard the aqueous layer. 5.2.7 Transfer quantitatively the combined petroleum extracts to the flask(
19、4.2). Evaporate to approximately5mL using the distillation apparatus(4.3). 5.2.8 Add to the flask(4.2)100mL of hot ethanol(3.1) neutralized to phenolphthalein and titrate with the sodium hydroxide solution(3.4) using the phenolphthalein indicator solution(3.6). 6 Expression of results The soap conte
20、nt, expressed as a percentage by mass, is given by the following expression: where V is the volume of the sodium hydroxide solution required (in mL); M is the mean relative molecular mass of the soap; m is the mass of the test portion (in g). V 0.1 M 1000 - 100 m - VM 0.01 m - =BS3762-3.9:1986 2 BSI
21、 12-1999 7 Precision No precision data are available. 8 Test report The test report shall include the following information: a) a reference to this BritishStandard, i.e.BS3762-3.9:1986; b) the results expressed in accordance with clause6, including the relative molecular mass used in the calculation
22、; c) a complete identification of the sample.BS3762-3.9:1986 BSI 12-1999 Publications referred to BS572, Specification for interchangeable conical ground glass joints. BS3591, Specification for industrial methylated spirits. BS3978, Specification for water for laboratory use. BS3762-3.9: 1986 BSI 38
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