1、BRITISH STANDARD BS 6829-3.1: 1989 ISO 6841:1988 Analysis of surface active agents (raw materials) Part 3: Sodium alkylbenzenesulphonates Section 3.1 Method for determination of mean relative molecular mass ISO title: Surface active agents Technical straight-chain sodium alkylbenzenesulfonates Deter
2、mination of mean relative molecular mass by gas-liquid chromatography UDC 661.185.1:543.2-112BS6829-3.1:1989 This British Standard, having been prepared under the directionof the Chemicals Standards Committee, was published under the authority ofthe Board of BSI and comesintoeffect on 31 March 1989
3、BSI 12-1999 First published February 1987 First revision March 1989 The following BSI references relate to the work on this standard: Committee reference CIC/34 Draft (ref 88/51829) announced in BSI News May 1988 ISBN 0 580 17142 6 Committees responsible for this British Standard The preparation of
4、this British Standard was entrusted by the Chemicals Standards Committee (CIC/-) to Technical Committee CIC/34, upon which the following bodies were represented: Chemical Industries Association Consumer Policy Committee of BSI Department of the Environment Department of Trade and Industry (Laborator
5、y of the Government Chemist) London Regional Transport Ministry of Defence Royal Society of Chemistry Soap and Detergent Industry Association Society of Dyers and Colourists Amendments issued since publication Amd. No. Date of issue CommentsBS6829-3.1:1989 BSI 12-1999 i Contents Page Committees resp
6、onsible Inside front cover National foreword ii Introduction 1 1 Scope 1 2 Normative reference 1 3 Principle 1 4 Reagents and materials 1 5 Apparatus 1 6 Sampling 2 7 Procedure 2 8 Examination of chromatograms 3 9 Expression of results 3 10 Test report 3 Figure 1 Safety tube with screw cap 4 Figure
7、2 Sealing the combustion tube 4 Figure 3 Typical chromatograms 5 Publications referred to Inside back coverBS6829-3.1:1989 ii BSI 12-1999 National foreword This Section of BS 6829 has been prepared under the direction of the Chemicals Standards Committee. It is identical with ISO 6841:1988 “Surface
8、active agents Technical straight-chain sodium alkylbenzenesulfonates Determination of mean relative molecular mass by gas-liquid chromatography”, published by the International Organization for Standardization (ISO). This Section of BS 6829 supersedes BS 6829-3.1:1987 which is withdrawn. The princip
9、al difference between this Section of BS 6829 and the 1987 edition is that attention is drawn to the fact that minor cyclic derivatives and branched-chain alkylbenzenes present are not taken into account in the calculation. Terminology and conventions. The text of the International Standard has been
10、 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 following. The comma has been used as a decimal marker. In British Standards it is curr
11、ent 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”. In British Standards it is current practice to use the spelling “sulphur”, etc., instead
12、of “sulfur”, etc. Wherever the words “International Standard” appear, referring to this standard, they should be read as “Section of BS 6829”. Cross-reference Additional information. With reference to clause 4, water complying with grade 3 of BS 3978 “Specification for water for laboratory use” is s
13、uitable. With reference to 4.1, the acid required is orthophosphoric acid. 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 used is in accordance with BS 6829-
14、3.1. 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 obligations. International Standard Corresponding
15、 British Standard ISO 607:1980 BS 3762 Analysis of formulated detergents Part1:1983 Methods of sample division (Identical) Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, pages1 to 6, an inside back cover and a back cover. This standard has been updated
16、 (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover.BS6829-3.1:1989 BSI 12-1999 1 Introduction When using the two-phase titration for the determination of anionic active matter content, it is necessary to know the me
17、an relative molecular mass of the substance. An accurate and rapid method consists of determining by gas-liquid chromatography (GLC) the mean relative molecular mass of the alkylbenzene used to manufacture the monosulfonated products; the relative molecular mass of the respective monosulfonate or mo
18、nosulfonic acid can then be calculated by adding the relative molecular mass of the SO 3 Na group minus Na, or that of the SO 3 H group minus H. The GLC technique is only applicable to straight-chain alkylbenzenes, since branched-chain types will give chromatograms from which it is impossible to ide
19、ntify and to calculate the relative molecular mass for individual chains. NOTEAny ortho-fused polycyclic hydrocarbon derivatives of low relative molecular mass present, such as indan, and tetrahydronaphthalene, as well as branched-chain alkylbenzenes, are not taken into account in the calculation of
20、 the relative molecular mass of the technical straight-chain sodium alkylbenzenesulfonate analysed. 1 Scope This International Standard specifies a gas-liquid chromatography (GLC) method for the determination of the mean relative molecular mass of technical straight-chain sodium alkylbenzenesulfonat
21、es. 2 Normative reference The following standard contains provisions which, through reference in this text, constitute provisions of this International Standard. At the time of publication, the edition indicated was valid. All standards are subject to revision, and parties to agreements based on thi
22、s International Standard are encouraged to investigate the possibility of applying the most recent edition of the standard listed below. Members of IEC and ISO maintain registers of currently valid International Standards. ISO 607:1980, Surface active agents and detergents Methods of sample division
23、. 3 Principle Desulfonation of a test portion in concentrated phosphoric acid medium and extraction of the liberated alkylbenzene with light petroleum. Determination of the mean relative molecular mass of the extracted alkylbenzene by GLC. Calculation of the mean relative molecular mass of the alkyl
24、benzenesulfonate. 4 Reagents and materials During the analysis, use only reagents of recognized analytical grade and only distilled water or water of equivalent purity. 4.1 Phosphoric acid, solution, 85 % (m/m). 4.2 Light petroleum, free from aromatic compounds, distilling between40and60 C. 4.3 Sodi
25、um sulfate, anhydrous. 4.4 Sodium hydroxide, 160 g/l solution. 4.5 Reference alkylbenzene: mixture of alkylbenzenes of known chain lengths, for example from C 15to C 21(phenyl group included). A product of known composition can be adopted as reference sample. This reference sample cannot be used for
26、 identification purposes but only for checking the proper performance of the chromatograph. 4.6 Carrier gas: nitrogen, helium, argon or hydrogen. 4.7 Acetone (if necessary). 5 Apparatus Usual laboratory equipment, and 5.1 Combustion tube, one end closed, of diameter12mm and length120mm. (Ready-made
27、tubes are available on the market.) 5.2 Test tubes, of similar dimensions to the combustion tube (5.1), fitted with a ground glass stopper. 5.3 Metallic safety tube, capable of accommodating the sealed combustion tube (5.1). It contains a cushioning disc (see the note) to prevent breakage of the com
28、bustion tube and is fitted with a screw cap (see Figure 1). NOTETo obtain the best cushioning effect, the disc should preferably be made of silicone rubber and polytetrafluoroethylene, although silicone rubber discs, of thickness3mm, are suitable. The use of polytetrafluoroethylene discs is not advi
29、sed. 5.4 Heating device: capable of being controlled at a temperature of about 250 C, for example a silicone oil bath. 5.5 Chromatograph, with the following elements: 5.5.1 Capillary column, of length 20 to 50 m, in spiral form, of internal diameter 0,25 mm and external diameter 1,1 mm, coated with
30、an apolar stationary phase for high temperatures (for example, a dimethylsiloxane type, such as siliconeOV 101), preconditioned at the test temperature; or a packed column, of length 1 to6m, provided that the chromatogram peaks are sufficiently well separated. 5.5.2 Flame ionization detectorBS6829-3
31、.1:1989 2 BSI 12-1999 5.5.3 Electronic integrator 5.5.4 Recorder 5.6 Syringe, of capacity 5 or 10 4l. 5.7 Pasteur pipette 6 Sampling The laboratory sample of surface active agent shall be prepared and stored in accordance with the instructions given in ISO 607. 7 Procedure 7.1 Test portion Weigh, to
32、 the, nearest 1 mg, into the combustion tube (5.1), 50 to 100 mg of the laboratory sample. 7.2 Desulfonation Add 2 ml of the phosphoric acid solution (4.1) to the combustion tube containing the test portion and seal the tube carefully using an oxygen/gas or oxygen/air flame. NOTEThe combustion tube
33、should be thoroughly sealed, with minimal reduction of wall thickness to avoid breakage during desulfonation. This is best done by slowly rotating the tube and heating it using an oxygen/gas or oxygen/air flame. As soon as the glass is sufficiently soft, gentle pressure should be applied to each end
34、 of the tube so as to thicken the wall. The ends of the tube are then pulled to obtain a capillary tube and it is finally sealed at point A (see Figure 2). Place the sealed tube in the safety tube (5.3) on the cushioning disc and close the safety tube with its screw cap. Place the safety tube for ap
35、proximately 15 min in the heating device (5.4), controlled at approximately250 C. Remove the safety tube, cool it in running water and remove the sealed combustion tube. Open the combustion tube and transfer its contents to one of the test tubes (5.2). Rinse the combustion tube with 2 ml of the ligh
36、t petroleum (4.2) and transfer the washings to the test tube. Stopper the test tube and shake it. Allow to settle and, using the Pasteur pipette (5.7), transfer the light petroleum layer to a second test tube (5.2). Add a further 2 ml of the light petroleum (4.2) to the first test tube, stopper it,
37、shake and allow to settle. Transfer, using the Pasteur pipette, the light petroleum layer to the second test tube. Add 1 ml of the sodium hydroxide solution (4.4) to the combined light petroleum extracts, stopper the test tube, shake it and allow to settle. Using the Pasteur pipette, transfer the li
38、ght petroleum layer to a third test tube (5.2). Wash the light petroleum extract three times more with 1 ml portions of the sodium hydroxide solution, rejecting the aqueous layer after each washing. Add approximately 1 g of the anhydrous sodium sulfate (4.3) to the light petroleum extract, stopper t
39、he test tube and shake. Transfer the light petroleum extract to another of the test tubes (5.2) and evaporate off most of the light petroleum by gently heating in a water bath controlled at 60 to 70 C. 7.3 Chromatographic analysis The following conditions are given as examples and have been found to
40、 be suitable. 7.3.1 Chromatograph settings 7.3.1.1 Injection Temperature greater than 210 C. 7.3.1.2 Column a) Isothermal conditions Temperature between 170 and 200 C according to the nature of the sample. b) Programmed conditions Initial temperature between 140 and 170 C, raised at a rate of 0,5 to
41、 2 C/min to the final temperature between 180 and210 C. 7.3.1.3 Carrier gas Flow rate between 0,3 and 40 ml/min according to the type and diameter of the column. 7.3.1.4 Detector conditions Temperature greater than 210 C 7.3.2 Instrument performance check Inject into the chromatograph sufficient of
42、the reference alkylbenzene (4.5) to give a chromatogram which exhibits all the anticipated peaks. Note the retention times and the separations obtained (for future comparison with the sample). 7.3.3 Test 7.3.3.1 Preparation of the test portion If the capillary column (5.5.1) is used, prepare a mixtu
43、re of 1 volume of the alkylbenzene extract(7.2) and 1 volume of acetone (4.7). If the packed column (5.5.1) is used, the alkylbenzene extract shall, if possible, be used directly, or otherwise diluted with the acetone up to 1 + 1. 7.3.3.2 Introduction of the test portion By means of the syringe (5.6
44、), inject into the chromatograph sufficient of the solution (7.3.1.1) to obtain a suitable chromatogram. Two typical chromatograms are shown in Figure 3.BS6829-3.1:1989 BSI 12-1999 3 8 Examination of chromatograms 8.1 Qualitative analysis Identify the components of the test portion by comparing the
45、test chromatogram with that for the reference alkylbenzene (4.5). 8.2 Quantitative analysis Determine the area of each peak corresponding to a particular chain length (or group of isomers) using the data from the integrator (5.5.3). Calculate the total peak area. 9 Expression of results 9.1 Method o
46、f calculation The area corresponding to a chain length or group of isomers, B i , expressed as a percentage of the total peak area, is given by the equation The mean relative molecular mass of the alkylbenzene is given by the formula where a i is the area of the peak corresponding to a chain length
47、or group of isomers; A is the total peak area; M r is the relative molecular mass of the isomers, the number of carbon atoms of which includes those in the phenyl group, as follows: Calculate the mean relative molecular mass of the alkylbenzenesulfonate by adding 102 to the calculated relative molec
48、ular mass of the alkylbenzene. 9.2 Precision Comparative analysis, on a sample of sodium alkylbenzene sulfonate, carried out in 10 laboratories, have given the following statistical result: 10 Test report The test report shall include the following information: a) all the information necessary for t
49、he 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) details of any operation not specified in this International Standard, or any operation regarded as optional, together with details of any incidents likely to have affected the results. M r C 15 204 C 16 218 C 17 232 C 18 246 C 19 260 C 20 274 C 21 288 mean (mean relative molecular mass) 340 standard deviation of repeatability, r 4 standard deviation of reproducibilit
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