1、BRITISH STANDARD BS3762-3.17: 1983 ISO4321:1977 Analysis of formulated detergents Part3:Quantitative test methods Section3.17 Method for determination of active oxygen content ISO title:Washing powders Determination of active oxygen content Titrimetric method NOTEIt is recommended that this Section
2、be read in conjunction with the information in the “General introduction”, published separately as BS3762-0. UDC 661.185:543.242.8:546.21BS3762-3.17:1983 This BritishStandard, having been prepared under the directionof the Chemicals Standards Committee, was published under the authority ofthe Board
3、of BSI and comesintoeffect on 30December1983 BSI12-1999 The committees responsible forthis BritishStandard are showninPart0. The following BSI references relate to the work on this standard: Committee reference CIC/34 Draft for comment75/53711 DC ISBN 0 580 13559 4 Amendments issued since publicatio
4、n Amd. No. Date of issue CommentsBS3762-3.17:1983 BSI 12-1999 i Contents Page National foreword ii 0 Introduction 1 1 Scope 1 2 Field of application 1 3 Reference 1 4 Principle 1 5 Reagents 1 6 Apparatus 1 7 Sampling 1 8 Procedure 1 9 Expression of results 2 10 Test report 2 Publications referred to
5、 Inside back coverBS3762-3.17:1983 ii BSI 12-1999 National foreword This Section of BS3762 has been prepared under the direction of the Chemicals Standards Committee. It is identical with ISO4321:1977 “Washing powders Determination of active oxygen content Titrimetric method”, published by the Inter
6、national Organization for Standardization (ISO). This Section supersedes section1, “Per-salts”, of method D9 of BS3762:1964. Section1 comprised2 methods: Method A. Determination by permanganate titration, and Method B. Determination by thiosulphate titration. The revised method utilizes the permanga
7、nate titrimetric procedure but differs from the original method A in the following respects: a) use of a one-twentieth aliquot from a solution of a comparatively larger mass of sample, thus reducing sampling errors; b) addition of bismuth and aluminium salts which improve the end-point with certain
8、detergent products; c) method of calculation of results (the original and revised methods calculate the per-salts in terms of hydrogen peroxide and oxygen respectively). Terminology and conventions. The text of the International Standard has been approved as suitable for publication as a BritishStan
9、dard without deviation. Some terminology and certain conventions are not identical with those used in BritishStandards; attention is drawn especially to the following. The comma has been used as a decimal marker. In BritishStandards, it is current practice to use a full point on the baseline as the
10、decimal marker. Wherever the words “International Standard” appear, referring to this standard, they should be read as “Section of this BritishStandard”. NOTEThe footnote to clause3 is no longer applicable now that ISO607 has been published. The Technical Committee has reviewed the provisions of ISO
11、1773 to which reference is made in clause6 and has decided that they are suitable for use in conjunction with this standard. A related BritishStandard to ISO1773 is BS2734 “Boiling flasks (narrow-necked), conical, flat bottom and round bottom”. Additional information. Reagents. With reference to cla
12、use5, water complying with BS3978 “Water for laboratory use” is suitable. Units relating to concentration. The units used in this standard are based on normality (N). The corresponding values, expressed as molar concentrations, are as follows: In9.1, the key to T would then read: “T is the exact con
13、centration in mol/l of the standard volumetric potassium permanganate solution(5.4) used”, the molar entity being 1 / 5 KMnO 4 . Cross-references International Standard Corresponding BritishStandard ISO607:1980 BS3762 Analysis of formulated detergents Part1:1983 Methods of sample reduction (Identica
14、l) ISO1042:1981 BS1792:1982 Specification for one-mark volumetric flasks (Identical) Clause As printed Expressed as molar concentration 5.2, 5.3 5N c ( 1 / 2H 2 SO 4 )=5mol/l 5.4 0,1N c ( 1 / 5 KMnO 4 )=0.1mol/lBS3762-3.17:1983 BSI 12-1999 iii This standard describes a method of test only and should
15、 not be referredto as a specification defining limits of purity. Reference to the standard should indicate that the method of test used is in conformity with BS3762-3.17. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are respons
16、ible 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, pagesi toiv, pages1and 2, an inside back cover and a back cover. This standard has been upd
17、ated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover.iv blankBS3762-3.17:1983 BSI 12-1999 1 0 Introduction Because of the specificity of washing powders and the relative stability of peroxyhydrates, the dissolutio
18、n of washing powders is likely to be incomplete and may result in a loss of oxygen; these disadvantages have been avoided by adoption of a particular method of dissolution appropriate to the determination of active oxygen content. 1 Scope This International Standard specifies a method for the determ
19、ination of the active oxygen content of commercial washing powders. 2 Field of application This method may be used for determining peroxyhydrates, for example sodium perborate; it should not be used for washing powders which contain, in addition to peroxyhydrates, products which react with acid perm
20、anganates under the analytical conditions. The method may be used in the presence of (ethylenedinitrilo)tetraacetic acid (EDTA) or otherchelating agents of the same type, provided that the concentration of these products does not exceed1% (m/m). 3 Reference ISO607, Surface active agents Detergents M
21、ethods of sample division 1) . 4 Principle Co-reduction, with liberation of oxygen, of the peroxyhydrate and potassium permanganate in an acid solution. NOTE 1The relatively long induction period that may occur with certain washing powders may be avoided by adding manganese sulphate. NOTE 2Bismuth n
22、itrate complexes with the EDTA or with any other amine acetate-based chelating agent, thus removing all possible interference. NOTE 3If aluminium sulphate is added, a preferential reaction with the condensed phosphates may be obtained, and the formation of a complex with the manganese ions, which ma
23、y occur in certain cases and which may lead to an end-point that is not sharp, may be avoided. 5 Reagents During the analysis, use only reagents of recognized analytical grade and only distilled water or water of equivalent purity. 5.1 Aluminium sulphate, octadecahydrate Al 2 (SO 4 ) 3 .18H 2 O. 5.2
24、 Sulphuric acid, solution containing bismuth and manganese. Dissolve2g of bismuth nitrate pentahydrate Bi(NO 3 ) 3 .5H 2 O and4g of manganese sulphate monohydrate (MnSO 4 .H 2 O) or an equivalent quantity of tetra- or pentahydrate (MnSO 4 .4H 2 O orMnSO 4 .5H 2 O) in1000ml of a5N sulphuric acid solu
25、tion. 5.3 (If necessary) Sulphuric acid, solution containing aluminium, bismuth and manganese. Dissolve50g of the aluminium sulphate(5.1),5g of bismuth nitrate pentahydrate and5g of manganese sulphate monohydrate in1000ml of a5N sulphuric acid solution. 5.4 Potassium permanganate (KMnO 4 ), freshly
26、standardized, approximately0,1N standard volumetric solution. 6 Apparatus Ordinary laboratory apparatus and 6.1 One-mark volumetric flask, of capacity1000ml, complying with the requirements of ISO1042. 6.2 Conical flask, of capacity500ml, complying with the requirements of ISO1773. 6.3 Mechanical st
27、irrer 7 Sampling The laboratory sample of washing powder shall be prepared and stored according to the instructions given in ISO607. 8 Procedure 8.1 Test portion Weigh, to the nearest0,01g, about10g of the laboratory sample. 8.2 Determination NOTE 1The determination shall be carried out as quickly a
28、s possible after dissolution of the test portion. NOTE 2With regard to the prescribed procedure for dissolution of the test portion, the usual rules of use of volumetric glassware are not respected here; in fact, a compromise has been adopted which allows the test portion to be dissolved in an appro
29、priate manner, depending on the nature of the determination. Transfer the test portion(8.1) to a2000ml beaker. Fill the one-mark volumetric flask(6.1) to the mark with water at35 to40 C and add to the test portion, allowing a few seconds for drainage. Stir vigorously with the stirrer(6.3) for3min to
30、 dissolve the test portion, apart from possible small amounts of insoluble silicate, etc. (solution L 1 ). 1) In preparation. (Revision of ISO/R607.)BS3762-3.17:1983 2 BSI 12-1999 During the operation of dissolution, place50ml of the sulphuric acid solution(5.2) in the conical flask(6.2) and add the
31、 potassium permanganate solution(5.4), drop by drop, with constant swirling until a permanent pale pink coloration appears. Using a pipette, take100,0ml of solution L 1and transfer it to the conical flask. Titrate with the potassium permanganate solution(5.4) until a pale pink colour, persisting for
32、 at least15s, appears. If the end-point is not sharp, repeat the determination in the presence of about1g of the aluminium sulphate(5.1) or using, for example,20ml of the sulphuric acid solution(5.3). 9 Expression of results 9.1 Method of calculation The active oxygen content of the washing powder i
33、s given, as a percentage by mass, by the formula where V is the volume, in millilitres, of the standard volumetric potassium permanganate solution(5.4) used for the determination; T is the exact normality of the standard volumetric potassium permanganate solution(5.4) used; m is the mass, in grams,
34、of the test portion(8.1). 9.2 Repeatability The maximum difference between the results of two determinations carried out in rapid succession on the same product by the same analyst, using the same apparatus, should not exceed1,3% of the mean value found for an active oxygen content of about2% (m/m).
35、 9.3 Reproducibility The maximum difference between results obtained on the same sample, in two different laboratories, should not exceed5% of the mean value found for an active oxygen content of about2% (m/m). 10 Test report The test report shall include the following particulars: a) all informatio
36、n necessary for the complete identification of the sample; b) the reference of the method used (reference to this International Standard); c) the results and the method of expression used; d) the test conditions; e) any operational details not included in this International Standard or regarded as o
37、ptional, as well as any incidents likely to have affected the results. V T 8,0 m -BS3762-3.17:1983 BSI 12-1999 Publications referred to See national foreword.BS3762-3.17: 1983 ISO4321:1977 BSI 389 Chiswick High Road London W4 4AL BSIBritishStandardsInstitution BSI is the independent national body re
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