1、BRITISH STANDARD BS EN 903:1994 BS6068-2.23: 1994 Water quality Determination of anionic surfactants by measurement of the methylene blue index MBAS The European Standard EN903:1993 has the status of a British Standard UDC 625.1/.3:620.1:543.3:661.185.1BSEN903:1994 This British Standard, having been
2、 prepared under the directionof the Environment andPollution Standards Policy Committee, was published underthe authority of the Standards Board and comes intoeffect on 15January1994 BSI 11-1999 The following BSI references relate to the work on this standard: Committee reference EPC/44 Draft announ
3、ced in BSI News January1991 ISBN 0 580 22082 6 Cooperating organizations The European Committee for Standardization (CEN), under whose supervision this European Standard was prepared, comprises the national standards organizations of the following countries: Austria Oesterreichisches Normungsinstitu
4、t Belgium Institut belge de normalisation Denmark Dansk Standardiseringsraad Finland Suomen Standardisoimisliito,r.y. France Association franaise de normalisation Germany Deutsches Institut fr Normunge.V. Greece Hellenic Organization for Standardization Iceland Technological Institute of Iceland Ire
5、land National Standards Authority of Ireland Italy Ente Nazionale Italiano di Unificazione Luxembourg Inspection du Travail et des Mines Netherlands Nederlands Normalisatie-instituut Norway Norges Standardiseringsforbund Portugal Instituto Portugus da Qualidade Spain Asociacin Espaola de Normalizaci
6、n y Certificacin Sweden Standardiseringskommissionen i Sverige Switzerland Association suisse de normalisation United Kingdom British Standards Institution Amendments issued since publication Amd. No. Date CommentsBSEN903:1994 BSI 11-1999 i Contents Page Cooperating organizations Inside front cover
7、National foreword ii Foreword 2 0 Introduction 3 1 Scope and field of application 3 2 References 3 3 Principle 3 4 Reagents 3 5 Apparatus 4 6 Sampling and samples 6 7 Procedure 6 8 Expression of results 8 9 Interferences 8 10 Test report 8 National annex NA (informative) Committees responsible Insid
8、e back cover National annex NB (informative) Cross-references Inside back cover Figure Gas-stripping apparatus 5 Table1 7BSEN903:1994 ii BSI 11-1999 National foreword This British Standard has been prepared under the direction of the Environment and Pollution Standards Policy Committee and is the En
9、glish language version of EN 903:1993 Water qualityDetermination of anionic surfactants by measurement of the methylene blue index MBAS, published by the European Committee for Standardization (CEN). It supersedes BS6068-2.23:1986, which is withdrawn. A British Standard does not purport to include a
10、ll 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 front cover, pages i an
11、d ii, theEN title page, pages2 to8, 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.EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN 903 Oc
12、tober1993 UDC 625.1/.3:620.1:543.3:661.185.1 Descriptors: Water, quality, water testing, chemical analysis, determination of content, surfactants, anionic surfactants, spectrophotometry analysis, sampling English version Water qualityDetermination of anionic surfactants by measurement of the methyle
13、ne blue index MBAS (ISO 7875-1:1984 modified) Qualit de leauDosage des agents de surface anioniques par mesurage de lindice au bleu de mthylne SABM (ISO 7875-1:1984modifie) WasserbeschaffenheitBestimmung von anionischen oberflchenaktiven Stoffen durch Messung des Methylenblau-Index (ISO 7875-1:1984
14、modifiziert) This European Standard was approved by CEN on1993-10-15. CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographi
15、cal references concerning such national standards may be obtained on application to the Central Secretariat or to any CEN member. This European Standard exists in three official versions (English, French, German). A version in any other language made by translation under the responsibility of a CEN
16、member into its own language and notified to the Central Secretariat has the same status as the official versions. CEN members are the national standards bodies of Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain,
17、Sweden, Switzerland and UnitedKingdom. CEN European Committee for Standardization Comit Europen de Normalisation Europisches Komitee fr Normung Central Secretariat: rue de Stassart 36, B-1050 Brussels CEN1993 Copyright reserved to CEN members Ref. No. EN 903:1993 EEN903:1993 BSI 11-1999 2 Foreword T
18、he text of the International Standard ISO7875-1:1984 Water qualityDetermination of surfactantsPart 1: Determination of anionic surfactants by the methylene blue spectrometric method prepared by ISO/TC147“Water quality” together with common modifications prepared by the Technical Committee CEN/TC230
19、“Water analysis” was submitted to the formal vote and approved by CEN as a European Standard. This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by April1994, and conflicting national standards shall be
20、 withdrawn at the latest by April1994. The standard was approved and in accordance with the CEN/CENELEC Internal Regulations, the following countries are bound to implement this European Standard: Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Nethe
21、rlands, Norway, Portugal, Spain, Sweden, Switzerland and UnitedKingdom.EN903:1993 BSI 11-1999 3 0 Introduction Natural and synthetic anionic surface-active substances may be determined as methylene-blue active substances (MBAS); they are referred to as MBAS index, a summary parameter method. 1 Field
22、 of application Under the experimental conditions, sulfonates and sulfates are the compounds chiefly measured, but some positive and negative interferences can occur (see clause9). The method is applicable to drinking water, surface water as well as waste water,e.g.for the determination of the prima
23、ry degradation of surfactants being under investigation in test systems containing natural or synthetic waste water. This applies for both laboratory scaled and technical waste water treatment plants. In the case of effluents originating from municipal waste water treatment plants, the MBAS index co
24、mprises not only synthetic but to a considerable extent also natural anionic surface active substances. The range of this method is applicable to concentrations of0,1 to5,0mg/l and the limit of detection is about0,05mg/l for solutions of standard surfactants in distilled water. 2 Normative reference
25、s This European Standard incorporates by dated or undated reference, provisions from other publications. These normative references are cited at the appropriate places in the text and the publication are listed hereafter. For dated references, subsequent amendment to or revisions of any of these pub
26、lications apply to this European Standard only when incorporated in it by amendment or revision. For undated references the latest edition of the publication referred to applies. EN 25667-2:1993, Water qualitySampling Part 2: Guidance on sampling techniques. ISO 5667-3:1985, Water qualitySampling Pa
27、rt3: Guidance on the preservation and handling of samples. 3 Principle Formation of salts from methylene blue and anionic surfactants in an alkaline medium. Extraction of these salts with chloroform and acid treatment of the chloroform solution. Elimination of any interferences by extraction of the
28、anionic surfactant-methylene blue complex from alkaline solutions and shaking with acidic methylene blue solution. Measurement of the absorbance of the separated organic phase at the maximum absorption wavelength of650nm. Evaluation by means of a calibration curve. For reasons of purity and stabilit
29、y the preferred standard is dodecyl benzene sulfonic acid methyl ester (tetrapropylene type, relative molecular mass340), although other calibration standards may be used (see the note to4.11). The calibration standard is prepared from the standard dodecyl benzene sulfonic acid ester after saponific
30、ation to the sodium salt. Calculation of the MBAS index as sodium dodecyl benzene sulfonate (see8.1). 4 Reagents During the analysis, unless otherwise stated, use only reagents of recognized analytical grade and only distilled water or water of equivalent purity. 4.1 Sodium chloride (NaCl). 4.2 Ethy
31、l acetate (C 4 H 8 O 2 ), freshly distilled. CAUTION. Ethyl acetate is flammable and toxic. 4.3 Chloroform (CHCl 3 ). CAUTION. Chloroform is a suspected carcinogen. If necessary for example, if it gives rise to high results in blank tests (7.2) purify the chloroform by filtration through Al 2 O 3(ne
32、utral grade, W200). NOTEDue to the toxicity of chloroform, it would be desirable to replace it by another solvent. Research work is going on. 4.4 Ethanol (C 2 H 5 OH),95% (V/V). 4.5 Methanol (CH 3 OH), freshly distilled. In order to avoid high results in blank tests (7.2) store in a glass bottle. 4.
33、6 Sulfuric acid (H 2 SO 4 ),0,5mol/l. 4.7 Ethanolic sodium hydroxide (NaOH), 0,1mol/l. Dissolve4gNaOH pellets in ethanol (4.4) and dilute with the same ethanol to1000ml.EN903:1993 4 BSI 11-1999 4.8 Neutral methylene blue, solution. NOTEThe solid methylene blue used should be the purest available. Di
34、ssolve0,350g methylene blue in water and dilute to1000ml. Prepare the solution at least24h before use. This solution is stable for at least2weeks. The absorbance of the chloroform phase of the blank test (see7.2) measured against chloroform shall not exceed0,02 per10mm layer thickness at650nm. In th
35、e case of higher blank absorbances, use other batches of methylene blue and/or purify the methylene blue solution by extraction as follows. Place the methylene blue solution in a suitably large separating funnel. For each100ml methylene blue solution, add200ml of buffer solution (4.10) and200ml of c
36、hloroform (4.3). Shake for30s and allow to separate. Run off the chloroform layer as completely as possible and rinse the aqueous layer without shaking with60ml of chloroform for each100ml methylene blue solution. Repeat the extraction and rinse as before. Discard the chloroform extracts; collect fo
37、r reuse after treatment. 4.9 Acid methylene blue, solution. Dissolve0,350g methylene blue in500ml of water and add6,50ml of sulfuric acid, =1,84g/ml. Dilute with water to1000ml after mixing. Prepare the solution at least24h before use. The absorbance of the chloroform phase of the blank test (see7.2
38、), measured against chloroform, shall not exceed0,02per10mm layer thickness at650nm. In the case of higher blank absorbances, either wash twice the methylene blue solution with chloroform for purification (see4.8) or use other batches of methylene blue. 4.10 Buffer solution, pH10. 4.10.1 Dissolve24g
39、 sodium hydrogen carbonate (NaHCO 3 ) and27g anhydrous sodium carbonate (Na 2 CO 3 ) in water and dilute to1000ml with water. 4.10.2 Alternatively, especially for water with high hardness, the following buffer solution may be used. 4.10.2.1 Disodium tetraborate (Na 2 B 4 O 7 .10H 2 O),0,05mol/l, sol
40、ution. Dissolve19g disodium tetraborate decahydrate in1000ml of water. This solution is stable for at least2weeks if stored in a glass stoppered bottle. 4.10.2.2 Sodium hydroxide (NaOH),0,1mol/l. Dissolve4g sodium hydroxide pellets in1litre of water. This solution is stable for at least2weeks if sto
41、red in a polyethylene stoppered glass bottle. 4.10.2.3 Alkaline borate solution Mix equal volumes of sodium tetraborate solution(4.10.2.1) and sodium hydroxide solution(4.10.2.2). This solution is stable for at least1week if stored in a polyethylene stoppered glass bottle. 4.11 Dodecyl benzene sulfo
42、nic acid methyl ester (tetra-propylene type) (C 19 H 32 O 3 S), stock standard solution. Weigh, preferably from a weighing pipette,400mg to450mg of dodecyl benzene sulfonic acid methyl ester to the nearest0,1mg into a round bottom flask, add50ml of ethanolic sodium hydroxide solution (4.7) and some
43、anti-bumping granules. Attach the reflux condenser and boil for1h. After cooling, rinse the condenser and the ground glass joint with about30ml of ethanol (4.4) and add the rinsings to the contents of the flask. Neutralize the solution with sulfuric acid (4.6) against phenolphthalein (4.12) until it
44、 becomes colourless. Transfer the solution to a1000ml one-mark volumetric flask, dilute to the mark with water and mix. This standard solution is stable for at least6months. NOTEAlthough the dodecyl benzene sulfonic acid methyl ester is preferable as it is a guaranteed non-hygroscopic standard, the
45、calibration graph (see7.3) may alternatively be established with the aid of the commercially available sodium salt of dodecane-1 sulfonic acid (C 12 H 25 NaO 3 S), dodecane-1 sulfuric acid (C 12 H 25 NaO 4 S) or dioctyl sulfosuccinic acid (C 20 H 37 NaO 7 S). 4.12 Phenolphthalein, indicator solution
46、. Dissolve1,0g phenolphthalein in50ml of ethanol(4.4) and add, while stirring continuously,50ml of water. Filter off any precipitate that forms. 5 Apparatus Ordinary laboratory equipment, and 5.1 pH-meter, with suitable electrodes made from glass. 5.2 Spectrometer, with selectors for discontinuous v
47、ariation, capable of measurement at650nm, equipped cells of optical path length with10 to50mm cells. 5.3 Gas-stripping apparatus (see the Figure; the apparatus is commercially available). The diameter of the sintered disc shall be the same as the internal diameter of the cylinder. NOTETo make cleani
48、ng easier, the apparatus should preferably be equipped with a spherical connection under the stripping funnel. The fixing member should also be divisible.EN903:1993 BSI 11-1999 5 Dimensions in millimetres. Figure Gas stripping apparatus (see the note to 5.3), V =1lEN903:1993 6 BSI 11-1999 Note on pr
49、eliminary cleaning of glassware All glassware should be washed thoroughly with water and then with ethanolic10% (m/m) hydrochloric acid and subsequently rinsed with water. 6 Sampling and samples Instructions for sampling are given in EN25667-2 and ISO5667-3. Do not withdraw samples through a foam layer. Use clean glass bottles, previously washed with methanol (4.5) for sampling and storage. Cooling to4 C is recommended for preservation over short periods. Consider the addition of a preservative if the sample is to be kept for more than2
