1、BRITISH STANDARD BS 6068-2.24: 1986 ISO 7875-2: 1984 Water quality Part 2: Physical, chemical and biochemical methods Section 2.24 Method for the determination of non-ionic surfactants using Dragendorff reagent ISO title: Water quality Determination of surfactants Part 2: Determination of non-ionic
2、surfactants using Dragendorff reagent UDC 566:614.777:628.1/.3:663.63:543.257.1:661.185.4BS6068-2.24:1986 This British Standard, having been prepared under thedirectionof the Environmentand PollutionStandards Committee,was published underthe authority of theboardofBSIand comesintoeffect on 31July198
3、6 BSI 10-1999 The following BSI references relate to the work on this standard: Committee reference EPC/44 Draft for comment 83/54482 DC ISBN 0 580 15159 X Amendments issued since publication Amd. No. Date of issue CommentsBS6068-2.24:1986 BSI 10-1999 i Contents Page National foreword ii 0 Introduct
4、ion 1 1 Scope 1 2 Field of application 1 3 References 1 4 Principle 1 5 Reagents 1 6 Apparatus 2 7 Sampling and samples 2 8 Procedure 2 9 Expression of results 4 10 Interferences 4 11 Test report 4 Annex A Bismuth determination 6 Figure Gas-stripping apparatus 5 Publications referred to Inside back
5、coverBS6068-2.24:1986 ii BSI 10-1999 National foreword This Section of this British Standard, which has been prepared under the direction of the Environment and Pollution Standards Committee, is identical with ISO 7875-2:1984 “Water quality Determination of surfactants Part 2: Determination of non-i
6、onic surfactants using Dragendorff reagent”. The International Standard was prepared by subcommittee2, Physical, chemical and biochemical methods, of Technical Committee147, Water quality, of the International Organization for Standardization (ISO) as a result of discussion in which the UK participa
7、ted. This British Standard is being published in a series of Parts subdivided into Sections that will generally correspond to particular International Standards. Sections are being, or will be, published in Parts1 to6 which, together with Part0, are as follows. Part 0: Introduction; Part 1: Glossary
8、; Part 2: Physical, chemical and biochemical methods; Part 3: Radiological methods; Part 4: Microbiological methods; Part 5: Biological methods; Part 6: Sampling. Terminology and conventions. The text of the International Standard has been approved as suitable for publication as a British Standard w
9、ithout 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. It is current practice in British Standards to use a full point on the baseline as the decim
10、al marker. Wherever the words “part of ISO7875” appear, referring to this standard, they should be read as “Section of BS6068”. In British Standards it is current practice to use the symbol “L” for litre (and its submultiples) rather than “l”, and to use the spelling “sulphur”, etc., instead of“sulf
11、ur”, etc. NOTETypographical error. In the note to6.3, lines 2 and 3, “subsequently” should be read as“subsequently”. Cross-references International Standards Corresponding British Standards BS 6068 Water quality ISO 5667-2:1982 Section 6.2:1983 Guidance on sampling techniques (Identical) ISO 5667-3:
12、1985 a Section 6.3:1986 Guidance on the preservation and handling of samples (Identical) ISO 7875-1:1984 Section 2.23:1986 Method for the determination of anionic surfactants by the methylene blue spectrometric method a This Part, referred to in the footnote to clause3 as being at the stage of draft
13、, has now been published.BS6068-2.24:1986 BSI 10-1999 iii Additional information. In the UK it is common practice to use a smaller apparatus than that shown in the Figure, although the diameter of the sintered disc and cylinder is identical, thereby ensuring a similar efficiency of stripping. A Brit
14、ish 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. Summary of pages This document comprises a fron
15、t cover, an inside front cover, pages i to iv, pages1to 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 in the amendment table on the inside front cover.iv blankBS6068-2.24:1986 BSI 10-1999
16、 1 0 Introduction Anionic and non-ionic surface active substances, generally called surfactants, are used in synthetic products for general cleaning purposes. ISO 7875 consists of the following parts: Part 1: Determination of anionic surfactants by the methylene blue spectrometric method; Part 2: De
17、termination of non-ionic surfactants using Dragendorff reagent. 1 Scope This part of ISO7875 specifies a method for the determination of non-ionic surfactants in aqueous media using Dragendorff reagent. 2 Field of application This part of ISO7875 applies to the determination of low concentrations of
18、 bismuth active substances (BiAS), i.e. non-ionic surfactants of the alkylphenol-alkylene oxide and alcohol-alkylene oxide adduct types, as long as they can be stripped and precipitated with Dragendorff reagent (for example ethoxylates with about5 to30 ethylene oxide groups per molecule). The method
19、 is suitable for influents and effluents of sewage treatment plants and waste water. When investigating surface waters it may be necessary to handle large sample volumes (up to5000ml). The detection limit is 0,05mg/l for a 1litre sample and the optimum range of application is250 to8004g. 3 Reference
20、s ISO 5667, Water quality Sampling Part 2: Guidance on sampling techniques Part 3: Guidance on the preservation and handling of samples 1) . 4 Principle Air stripping of surfactants from the sample and collection in ethyl acetate. Removal of ethyl acetate and precipitation of the non-ionic surfactan
21、ts with Dragendorff reagent (KBil 4+ BaCl 2+ acetic acid). Isolation and dissolution of the precipitate, and potentiometric determination of the concentration of bismuth equivalent to the concentration of non-ionic surfactant with sodium pyrrolidin-1-yl dithiocarboxylate solution. Alternative method
22、s for the determination of the bismuth ion are, among others, atomic absorption and UV spectrometry (see the Annex A). 5 Reagents During the analysis, unless otherwise stated, use only reagents of recognized analytical grade, and only distilled water or water of equivalent purity. 5.1 Sodium chlorid
23、e (NaCl). 5.2 Sodium hydrogencarbonate (NaHCO 3 ). 5.3 Ethyl acetate (C 4 H 8 O 2 ), freshly distilled. CAUTION Ethyl acetate is flammable and toxic. 5.4 Methanol (CH 3 OH), freshly distilled, stored in a glass bottle. 5.5 Glacial acetic acid (CH 3 COOH), = 1,05g/ml. Lower concentrations are not sui
24、table. 5.6 Hydrochloric acid Add 1ml HCl ( = 1,12g/ml) to 100ml water. 5.7 Methanolic hydrochloric acid Dilute 10ml HCl ( = 1,12g/ml) with methanol (5.4) to 100ml. 5.8 Sulfuric acid (H 2 SO 4 ), 0,5 mol/l. 5.9 Ammonia, solution. Add 10,0ml ammonia solution, ( = 0,91g/ml) to250ml water. 5.10 Ammonium
25、 tartrate, solution. Add 12,40g tartaric acid (C 4 H 6 O 6 ) to12,40g ammonia solution ( = 0,91g/ml) and dilute to1000ml with water. 5.11 Solution A Dissolve 1,70g bismuth(III) oxynitrate monohydrate (BiONO 3 H 2 O) in 20ml glacial acetic acid (5.5) and dilute to 100ml with water. Dissolve 65,0g pot
26、assium iodide (KI) in about200ml water. Mix both solutions in a 1000ml one-mark volumetric flask, add 200ml glacial acetic acid (5.5) and dilute to the mark with water. The solution is stable for about 1 week when stored in the dark. 5.12 Solution B Dissolve 290,0g barium chloride dihydrate (BaCl 2
27、2H 2 O) in 1000ml water. 5.13 Precipitating agent Mix two parts by volume of solution A (5.11) with one part by volume of solution B (5.12). The solution is stable for about 1 week if stored in a brown glass bottle. 1) At present at the stage of draft.BS6068-2.24:1986 2 BSI 10-1999 5.14 Standard ace
28、tate buffer Dissolve 40,0g sodium hydroxide (NaOH) in about500ml water. Add 120ml glacial acetic acid(5.5). Mix thoroughly, cool, and dilute with water to1000ml in a volumetric flask. 5.15 Sodium pyrrolidin-1-yl dithiocarboxylate, 0,5mmol/l solution. Dissolve 103,0mg sodium pyrrolidin-1-yl dithiocar
29、boxylate dihydrate (C 5 H 8 NS 2 Na2H 2 O) in about 500ml water. Add 10,0ml amyl alcohol (C 5 H 11 OH) and0,50g sodium hydrogencarbonate(5.2), dilute with water to1000ml. 5.16 Copper(II) sulfate, stock solution. Dissolve 1,249g copper(II) sulfate pentahydrate (CuSO 4 5H 2 O) in 50ml sulfuric acid (5
30、.8) and200ml water, and dilute with water to1000ml. Do not use broken or soft crystals. 5.17 Copper(II) sulfate, standard solution. Dilute 50,0ml of the copper stock solution (5.16) and 10ml sulfuric acid (5.8) with water to 1000ml. 5.18 Bromocresol purple, solution. Dissolve 0,10g dye in 100ml meth
31、anol (5.4). 5.19 Cation exchange resin, SO 3 H +form (50to100mesh = 0,15to0,30mm), alcohol-resistant. 6 Apparatus Ordinary laboratory equipment, and 6.1 Gas-stripping apparatus (see the Figure; the apparatus is commercially available). The diameter of the sintered disc shall be of the same size as t
32、he internal diameter of the cylinder. NOTETo make cleaning easier, the apparatus should preferably be equipped with a spherical connection under the stripping funnel. The steady should also be divisible. 6.2 Ion exchange column, of diameter 16mm, and height 200mm. 6.3 Recording potentiometer, with p
33、latinum/calomel or platinum/silver chloride electrodes, range250mV, with automatic burette, 20to 25ml capacity, or appropriate manual equipment. NOTE ON PRELIMINARY CLEANING OF GLASSWARE All glassware should be washed thoroughly with water and then with ethanolic10% (m/m) hydrochloric acid and subse
34、quenty rinsed with water. 7 Sampling and samples Instructions for sampling are given in ISO 5667-2 and ISO 5667-3. Samples should not be withdrawn through a foam layer. Clean glass bottles, previously washed with methanol (5.4) should be used for sampling and storage. Cooling to4 C is recommended fo
35、r preservation over short periods. The addition of a preservative should be considered if the sample is to be kept for more than24h. The addition of 1% (V/V) of a40% (V/V) formaldehyde solution is suitable for periods up to4days while saturating with chloroform is suitable for periods up to8days. Te
36、st samples should normally be free of suspended matter which can be separated by centrifugation; however, it has to be appreciated that, as a result of such a separation, surfactant adsorbed on suspended matter will not be determined. 8 Procedure 8.1 Concentration and separation of the surfactant In
37、stall the apparatus (6.1) in a well ventilated hood to carry off ethyl acetate vapour. The laboratory samples should be centrifuged if considerable amounts of suspended matter more than0,3g/l are present. Place a measured quantity of the laboratory sample (the test sample) containing between200 and1
38、0004g non-ionic surfactant, into the stripping apparatus. Weigh out 100 g sodium chloride (5.1) and5g sodium hydrogencarbonate (5.2). If the test sample volume exceeds500ml, add these salts in solid form and dissolve by passing nitrogen gas or air through it. If a smaller test sample volume is used,
39、 dissolve the salts in400ml water and add in solution. If necessary, add water up to the level of the upper stopcock. Add 100 ml ethyl acetate (5.3). Fill the wash bottle in the gas line (nitrogen or air) two-thirds full with ethyl acetate. Pass a gas stream of20to50 l/h through the apparatus. The u
40、se of a variable area flowmeter 2)is recommended. The gas flow should be adjusted in such a way that phases remain separate and no turbulence is produced at the interface. Thus significant mixing of the phases and solution of ethyl acetate in the water is avoided. Stop the gas flow after5min. If a l
41、oss of more than20% (V/V) of the organic phase has occurred due to solution in the water phase, discard the test sample. 2) The commonly used term “Rotameter” is a trade name.BS6068-2.24:1986 BSI 10-1999 3 Run off the organic phase completely into a separating funnel. Any water in the separating fun
42、nel it should only be a few millilitres is returned to the stripping apparatus. Filter the ethyl acetate solution through a dry qualitative filter paper into a flask (250ml). Add a further100ml ethyl acetate to the stripping apparatus and again pass nitrogen or air for5min. Separate the organic laye
43、r as given above, using the same separating funnel, filter, and add it to the first portion. Rinse the filter and funnel with25ml ethyl acetate. Remove all the ethyl acetate solution on a water-bath under a hood. To speed up the process direct a gentle air stream over the surface of the solution. 8.
44、2 Blank test With each series of samples, carry out a blank test in parallel with the determination, using5ml methanol (5.4) and40ml water instead of the test portion. The consumption of sodium pyrrolidin-1-yl dithiocarboxylate solution should be less than1ml; otherwise the reagents shall be checked
45、 for their content of heavy metals. 8.3 Precipitation and filtration Dissolve the dry residue from8.1 after the removal of any interferences (see clause10) in5ml methanol (5.4), transfer to a beaker, add40ml water and0,5ml hydrochloric acid (5.6), stir with a magnetic stirrer, and add from a measuri
46、ng cylinder30ml precipitating agent (5.13). The precipitate is formed during continuous stirring. Discontinue stirring after10min and wait for at least5min. Place a sintered glass crucible (porosity4, capacity40ml) into a suitable adapter attached to a500ml filter flask. A glass-fibre filter paper m
47、ay also be inserted; this prolongs the life of the crucible. Wet the filter under suction with about2ml glacial acetic acid (5.5). Filter the precipitate through the crucible. (It is essential that rubber collars, if used, do not come into contact with any of the reagents.) The use of a polyethylene
48、 squirt bottle for the acetic acid is recommended. It is not necessary to transfer the precipitate quantitatively on to the filter because a solution of the precipitate (see8.4) is transferred back to the same beaker prior to titration, thereby ensuring that any precipitate remaining in the beaker a
49、lso becomes dissolved. 8.4 Dissolution of the precipitate Place the crucible in a glass adapter on a250ml filter flask. Dissolve the precipitate by adding hot (at approximately80 C) ammonium tartrate solution (5.10) in three portions of10ml. Pour the contents of the filter flask into the beaker with an additional20ml of hot tartrate solution to dissolve any remaining precipitate. Carefully wash the crucible, adapter, and the filter flask with a further20ml of hot tartrate solution to dissolve any remaining precipitate.
