1、BRITISHSTANDARD BS3762-3.23: 1990 ISO4325:1990 Analysis of formulated detergents Part 3: Quantitative test methods Section 3.23 Method for determination of chelating agents content NOTEIt is recommended that this Section be read in conjunction with the information in the “General introduction”, publ
2、ished separately as BS3762-0.BS3762-3.23:1990 This BritishStandard, having been prepared under the directionof the Chemicals Standards Policy Committee, waspublished under the authorityof the Board ofBSIandcomes into effect on 31August1990 BSI 12-1999 First edition September 1986 Second edition Augu
3、st 1990 The following BSI references relate to the work on this standard: Committee reference CIC/34 Draft for comment89/50125 DC ISBN 0 580 18837 X Committees responsible for this BritishStandard The preparation of this BritishStandard was entrusted by the Chemicals Standards Policy Committee (CIC/
4、-) to Technical Committee CIC/34, upon which the following bodies were represented: Chemical Industries Association Chemical Industries Association (GOSIP) Department of Trade and Industry (Laboratory of the Government Chemist) Ministry of Defence Royal Society of Chemistry Soap and Detergent Indust
5、ry Association Society of Dyers and Colourists Amendments issued since publication Amd. No. Date CommentsBS3762-3.23:1990 BSI 12-1999 i Contents Page Committees responsible Inside front cover National foreword ii 1 Scope 1 2 Normative references 1 3 Principle 1 4 Reagents 1 5 Apparatus 1 6 Sampling
6、1 7 Procedure 1 8 Expression of results 1 9 Test report 2 Publication(s) referred to Inside back coverBS3762-3.23:1990 ii BSI 12-1999 National foreword This Section of BS3762 has been prepared under the direction of the Chemicals Standards Policy Committee. It is identical with ISO4325:1990 “Soaps a
7、nd detergents Determination of chelating agent content Titrimetric method”, published by the International Organization for Standardization (ISO). This Section supersedes BS3762-3.23:1986, which is withdrawn. ISO4325:1990 was based on the1986 edition of BS3762-3.23, which is equivalent in technical
8、content to this edition. The Technical Committee has reviewed the provisions of ISO385-1, to which reference is made in5.2 and has decided that they are acceptable for use in conjunction with this standard. A related BritishStandard to ISO385-1 is BS846:1985 “Specification for burettes”. NOTEBurette
9、s of class A accuracy in accordance with BS846:1985 may be used in place of burettes complying with class A of ISO385-1. This Section 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
10、of test used is in accordance with BS3762-3.23. 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 immunity from legal obliga
11、tions. Cross-references International Standard Corresponding BritishStandard ISO607:1980 BS3762 Analysis of formulated detergents Part1:1983 Methods of sample division (Identical) ISO3696:1987 BS3978:1987 Specification for water for laboratory use (Identical) Summary of pages This document comprises
12、 a front cover, an inside front cover, pagesi andii, pages1 and2, 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.BS3762-3.23:1990 BSI 12-1999
13、1 1 Scope This International Standard specifies a method of analysis for the determination of the chelating agent content of detergent compositions and soaps containing not more than2% (m/m) of chelating agent. Ethylenediaminetetraacetic acid (EDTA) is one of the most widely used chelating agents an
14、d the method has been designed principally for determining this compound and its salts. Before determining other chelating agents, or determining ethylenediaminetetraacetic acid in the presence of other chelating agents, the applicability of the method should be confirmed. 2 Normative references The
15、 following standards contain provisions which, through reference in this text, constitute provisions of this International Standard. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this International Standard ar
16、e encouraged to investigate the possibility of applying the most recent editions of the standards indicated below. Members of IEC and ISO maintain registers of currently valid International Standards. ISO385-1:1984, Laboratory glassware Burettes Part1: General requirements. ISO607:1980, Surface acti
17、ve agents and detergents Methods of sample division. ISO3696:1987, Water for analytical laboratory use Specification and test methods. 3 Principle A test portion of the sample is dissolved in water, the pH of the solution adjusted to4,65 and the solution titrated against standard copper(II) sulfate
18、solution using1-(2-pyridylazo)-2-naphthol as indicator. 4 Reagents During the analysis, use only reagents of recognized analytical grade and water of purity grade3 as defined in ISO3696. 4.1 Hydrochloric acid solution, c(HCl)=5mol/l. 4.2 Acetate buffer solution, pH=4,65. Mix equal volumes of acetic
19、acid solution, c(CH 3 COOH)=0,4mol/l, and sodium hydroxide solution, c(NaOH)=0,2mol/l. 4.3 PAN indicator,0,1% (m/m) solution of1-(2-pyridylazo)-2-naphthol in ethanol. Do not keep this solution longer than7days. 4.4 Copper(II) sulfate, standard volumetric solution, c(CuSO 4 )=0,0100mol/l. Weigh out,
20、to the nearest1mg,2,497g of copper(II) sulfate pentahydrate (CuSO 4 .5H 2 O), of minimum purity99,5% (m/m) and dissolve in water. Quantitatively transfer the solution obtained to a1000ml one-mark volumetric flask, dilute to the mark and mix. 5 Apparatus Ordinary laboratory apparatus and 5.1 pH-meter
21、, with electrodes and stirrer. 5.2 Burette, capacity50ml, complying with the requirements of class A of ISO385-1. 6 Sampling The laboratory sample of soap or detergent shall be prepared and stored in accordance with the instructions given in ISO607. 7 Procedure 7.1 Test portion Weigh, to the nearest
22、0,1g,10g of the laboratory sample into a beaker or conical flask. 7.2 Determination Add100ml of water to the test portion, warm and stir to dissolve. Introduce the electrodes, connected to the previously calibrated pH-meter(5.1), and add hydrochloric acid solution(4.1) until the pH is4,6 0,5. Raise,
23、 rinse and remove the electrodes. NOTE 1In most cases, there is no interference by other components of the product, for example fatty acids, but if necessary the fatty acids of soaps may be removed by filtration through a wet filter paper. Add5ml of the acetate buffer solution(4.2) and0,4ml of the P
24、AN indicator solution(4.3). Heat to about60 C and titrate with the copper(II) sulfate solution(4.4) until the indicator changes from yellow to wine-red. NOTE 2The wine-red colour should persist for at least1min. A fading end-point suggests that some other chelating agent is present. 8 Expression of
25、results 8.1 Calculation The chelating agent content, expressed as a percentage by mass of ethylenediaminetetraacetic acid (EDTA), is given by the following formula: where V is the volume, in millilitres, of the copper(II) sulfate solution(4.4) used for the titration; Vc 10 3 -292 100 m - BS3762-3.23
26、:1990 2 BSI 12-1999 8.2 Precision 8.2.1 Repeatability The maximum difference found between the results of two determinations carried out on the same sample in rapid succession by the same analyst using the same apparatus should not be more than0,01% (m/m) for EDTA contents up to2% (m/m). 8.2.2 Repro
27、ducibility The maximum difference between two results obtained on the same sample, in two different laboratories, should not differ by more than0,06%(m/m) for liquid soaps, for EDTA contents up to2%(m/m), and by0,04% (m/m) for detergents, for EDTA contents up to2% (m/m). 9 Test report The test repor
28、t shall include the following information: a) all information necessary for the complete identification of the sample; b) the method used (i.e.a reference to this International Standard); c) the results and the way in which they have been expressed; d) any operational details which are not specified
29、 in this International Standard or in the International Standards to which reference is made, or which are regarded as optional, as well as any incidents liable to have affected the results. c is the actual concentration, expressed in moles of CuSO 4per litre, of the copper(II) sulfate solution used
30、; m is the mass, in grams, of the test portion(7.1); 292 is the relative molecular mass of ethylenediaminetetraacetic acid.BS3762-3.23:1990 BSI 12-1999 Publication(s) referred to Seenational foreword.BS3762-3.23: 1990 ISO4325:1990 BSI 389 Chiswick High Road London W4 4AL BSIBritishStandardsInstituti
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