1、BRITISH STANDARD BS 6829-4.3: 1990 ISO 2270:1989 Analysis of surface active agents (raw materials) Part 4: Ethylene oxide adducts Section 4.3 Method for determination of oxyethylene groups UDC 661.185.1:543.2 112BS6829-4.3:1990 This British Standard, having been prepared under the directionof the Ch
2、emicals Standards Policy Committee, waspublished under the authorityof the Board of BSIandcomes into effect on 31 January 1990 BSI 12-1999 First published August 1988 Second edition January 1990 The following BSI references relate to the work on this standard: Committee reference CIC/34 Draft (ref.
3、89/51584) announced in BSI News, June 1989 ISBN 0 580 18071 9 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: C
4、hemical 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 Colourists Amendments issu
5、ed since publication Amd. No. Date of issue CommentsBS6829-4.3:1990 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 Reactions 1 5 Reagents 1 6 Apparatus 1 7 Procedure 2 8 Expression of results 2 9 Test repo
6、rt 3 Figure 1 Details of glassware 4 Figure 2 Assembled apparatus 5 Publications referred to Inside back coverBS6829-4.3:1990 ii BSI 12-1999 National foreword This Section of BS6829has been prepared under the direction of the Chemicals Standards Policy Committee and supersedes BS6829-4.3:1988, which
7、 is withdrawn. It is identical with ISO2270:1989 “Non-ionic surface active agents Polyethoxylated derivatives Iodometric determination of oxyethylene groups”, published by the International Organization for Standardization (ISO). The differences between this Section of BS6829and the1988edition are e
8、ditorial, except that an ambiguity in the temperature used for the decomposition of the ethylene di-iodide has been removed. The relevant requirements of ISO385-1:1984 are technically equivalent to those in BS846:1985 “Specification for burettes”. Additional information. With reference to clause5, w
9、ater complying with grade3of BS3978 “Specification for water for laboratory use” is suitable. With reference to 5.7, it is current practice in the UK to use freshly prepared starch solution of similar concentration but without the addition of mercury (II) iodide. This Section describes a method of t
10、est 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 used is in accordance with BS6829-4.3. A British Standard does not purport to include all the necessary provisions of a contract. Users of British
11、 Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Cross-reference International Standard Corresponding British Standard ISO 383:1976 BS 572:1985 Specification for interchangeable conical ground glas
12、s joints (Technically equivalent) Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, pages 1 to 6, 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 i
13、n the amendment table on the inside front cover.BS6829-4.3:1990 BSI 12-1999 1 1 Scope This International Standard specifies a method for the iodometric determination of oxyethylene groups in polyethoxylated non-ionic surface active agents. The method is applicable to the analysis of polyethoxylated
14、derivatives of primary saturated fatty alcohols; oleyl alcohol; saturated fatty acids; straight and branched chain alkylphenols. It is also applicable in the presence of unreacted alcohols, fatty acids or alkylphenols of the types mentioned above. The method is not applicable in the presence of comp
15、ounds containing sulfur or nitrogen; compounds containing oxygen or halogen atoms on adjacent carbon atoms other than as oxyethylene groups, for example compounds containing oxypropylene groups; aldehydes or acetals; sterols and derivatives. 2 Normative references The following standards contain pro
16、visions 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 are encouraged to investigate the
17、possibility of applying the most recent editions of the standards listed below. Members of IEC and ISO maintain registers of currently valid International Standards. ISO 383:1976, Laboratory glassware Interchangeable conical ground glass joints. ISO 385-1:1984, Laboratory glassware Burettes Part 1:
18、General requirements. 3 Principle Hydrolysis of the oxyethylene groups by nascent hydriodic acid. Liberation of the iodine and titration with a standard volumetric sodium thiosulfate solution. 4 Reactions The basic reaction is the conversion of each (CH 2 -CH 2 O) group to ethylene di-iodide (ICH 2
19、-CH 2 I), in accordance with the equation RO-(CH 2 -CH 2 O) n H + 2nHI F nICH 2 -CH 2 I + ROH + nH 2 O The unstable ethylene di-iodide is then decomposed on heating: ICH 2 -CH 2 I F C 2 H 4+ I 2 NOTEIf R is an alkyl radical, ROH will be converted to RI. Some of the ethylene groups (and all of any ol
20、eyl alcohol present) will react with HI to form a stable iodide. 5 Reagents During the analysis, use only reagents of recognized analytical grade and only distilled water or water of equivalent purity. 5.1 Nitrogen or carbon dioxide 5.2 Potassium iodide, crystals, minimum purity99,5%. 5.3 Phosphoric
21、 acid, 20approximately1,70g/ml. 5.4 Methanol, 20 0,79g/ml. 5.5 Potassium iodide,100g/l solution. 5.6 Sodium thiosulfate, standard volumetric solution, c(Na 2 S 2 O 3 )=0,1mol/l. 5.7 Starch, indicator solution. Mix5g of starch and10g of mercury(II) iodide with30ml of water; add this mixture to1litre
22、of boiling water and boil for3min. 6 Apparatus Ordinary laboratory apparatus and: 6.1 Round-bottom flask (seeFigure 1 andFigure 2), capacity 50ml, with a central neck fitted with a 19/26 conical ground-glass socket and a side neck fitted with a 14/23 conical ground-glass socket. The conical ground-g
23、lass joints shall comply withISO383. 6.2 Gas inlet tube (seeFigure 1 andFigure 2), with a 14/23; conical ground-glass cone terminating in a length of at least20mm of tubing of1,5mm internal diameter. When fitted to the flask (6.1), the tube shall end about10mm above the bottom of the flask. 6.3 Wate
24、r-cooled reflux condenser (seeFigure 1 andFigure 2), with a nominal length of200mm to500mm, a 19/26 conical ground-glass cone at the bottom and a 14/23 conical ground-glass socket, attached at an angle of45 , at the top (seeFigure 1)The conical ground-glass joints shall comply withISO383. 6.4 Absorp
25、tion bulbs (seeFigure 1 andFigure 2), of capacity7ml to10ml. 6.5 Sample introduction rod (seeFigure 1), comprising a solid glass rod with a wide-mouthed hollow cone at one end. 6.6 Oil bath, capable of being maintained at a temperature of165 C 1 C.BS6829-4.3:1990 2 BSI 12-1999 6.7 Flow meter, capabl
26、e of measuring flow rates in the region of0,5ml/s. 6.8 Burette, capacity50ml, complying with class A ofISO385-1. 7 Procedure 7.1 Test portion Weigh, to the nearest0,1mg, into the cone of the sample introduction rod (6.5) 60mg to300mg of the sample in the case of a product containing less than33% (m/
27、m) of ethylene oxide; sufficient of the sample to contain20mg to100mg of ethylene oxide, in the case of a product containing more than33% (m/m) of ethylene oxide. 7.2 Determination Invert the flask (6.1) over the sample introduction rod containing the test portion (see7.1), then turn the flask uprig
28、ht, allowing the rod to slide into the flask so that its cavity end is at the bottom of the flask. Add3g of the potassium iodide (5.2). Attach the inlet tube (6.2) and the condenser (6.3) to the flask, using a little of the phosphoric acid (5.3) to lubricate the ground-glass joints. Pass a stream of
29、 the nitrogen or carbon dioxide (5.1) into the flask at a flow rate greater than0,5ml/s for at least20min. Without interrupting the gas flow or removing the condenser, place the flask in the oil bath (6.6) maintained at165 C 1 C. Reduce the gas flow rate to between0,1ml/s and0,5ml/s. Add, via the co
30、ndenser,5ml of the phosphoric acid (5.3) to the flask. Fill the absorption bulbs (6.4) with a suitable quantity (7ml to10ml) of the potassium iodide solution (5.5) and attach them to the condenser. Allow the reaction to proceed for30min, ensuring that the oil bath does not exceed the specified tempe
31、rature during the last20min. Remove the flask from the source of heat, without interrupting the gas flow, and allow to cool to below80 C. Stop the flow of nitrogen or carbon dioxide. Quickly turn the absorption bulbs about the axis of the joint so that their contents flow down the condenser into the
32、 flask. Turn the bulbs back to their original position. Introduce another7ml to10ml of the potassium iodide solution into the absorption bulbs and again turn them so that the contents flow down the condenser into the flask. Remove the absorption bulbs. Rinse the condenser and its lower joint with a
33、few millilitres of the potassium iodide solution, collecting the rinsings in the flask, and remove the condenser. Similarly, rinse and remove the gas inlet tube. Transfer quantitatively the contents of the round-bottom flask to a250ml conical flask, rinsing with water and a few millilitres of the po
34、tassium iodide solution. If a sparingly soluble residue is seen, dissolve this in a few millilitres of the methanol (5.4). Titrate with the standard volumetric sodium thiosulfate solution (5.6), adding the starch indicator solution (5.7) when the iodine colour has nearly disappeared. 7.3 Blank test
35、Carry out a blank test in parallel with the determination, using the same reagents and following the same procedure as for the determination, but omitting the test portion. 8 Expression of results 8.1 Calculation The oxyethylene content, expressed as a percentage by mass, is given by the formula whe
36、re V 0 is the volume, in millilitres, of the sodium thiosulfate solution (5.6), used for the blank test (see7.3); V 1 is the volume, in millilitres, of the sodium thiosulfate solution (5.6), used for the determination (7.2);BS6829-4.3:1990 BSI 12-1999 3 c is the exact concentration, in moles of Na 2
37、 S 2 O 3per litre, of the sodium thiosulfate solution (5.6); m is the mass, in grams, of the test portion(7.1); 0,022is the mass, in grams, of oxyethylene corresponding to1,00ml of sodium thiosulfate solution, c(Na 2 S 2 O 3 ) =1,000mol/l. 8.2 Precision 8.2.1 Repeatability The maximum difference fou
38、nd between the results of two determinations carried out on the same product simultaneously by the same analyst using the same apparatus should not exceed1,5% of the average value for derivatives containing more than10% (m/m) of ethylene oxide. 8.2.2 Reproducibility The difference between the result
39、s obtained with the same sample in two different laboratories should not exceed3% of the average value for derivatives containing more than10% (m/m) of ethylene oxide. 9 Test report The test report shall include be following information: a) all information necessary for the complete identification o
40、f the sample; b) the method used (a reference to this International Standard); c) the results obtained, as well as the units in which they have been expressed; d) any operational details not specified in this International Standard or in the International Standards to which reference is made, as wel
41、l as any optional operations and any incidents likely to have influenced the results.BS6829-4.3:1990 4 BSI 12-1999 Figure 1 Details of glasswareBS6829-4.3:1990 BSI 12-1999 5 NOTEFor key, seeFigure 1. Figure 2 Assembled apparatus6 blankBS6829-4.3:1990 BSI 12-1999 Publications referred to See national
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