《BS-6068-2.48-1995 ISO-10359-2-1994.pdf》由会员分享，可在线阅读，更多相关《BS-6068-2.48-1995 ISO-10359-2-1994.pdf（12页珍藏版）》请在三一文库上搜索。
1、BRITISH STANDARD BS 6068-2.48: 1995 ISO 10359-2: 1994 Water quality Part 2: Physical, chemical and biochemical methods Section 2.48 Determination of inorganically bound total fluoride after digestion and distillation Licensed Copy: sheffieldun sheffieldun, na, Tue Dec 05 01:30:42 GMT+00:00 2006, Unc
2、ontrolled Copy, (c) BSI BS 6068-2.48:1995 This British Standard, having been prepared under the direction of the Health and Environment Sector Board, was published under the authority of the Standards Board and comes into effect on 15 April 1995 BSI 07-1999 The following BSI references relate to the
3、 work on this standard: Committee reference EPC/44 Draft for comment 92/58404 DC ISBN 0 580 23959 4 Committees responsible for this British Standard The preparation of this British Standard was entrusted to Technical Committee EPC/44, Water quality, upon which the following bodies were represented:
4、Association of Consulting Scientists British Association for Chemical Specialists British Gas plc Chemical Industries Association Convention of Scottish Local Authorities Department of the Environment (Water Directorate) Department of the Environment for Northern Ireland Department of Trade and Indu
5、stry (Laboratory of the Government Chemist) Electricity Association Industrial Water Society Institute of Gas Engineers Institution of Water Officers Institution of Water and Environmental Management National Rivers Authority Royal Institute of Public Health and Hygiene Royal Society of Chemistry Sc
6、ottish Association of Directors of Water and Sewerage Services Soap and Detergent Industry Association Water Companies Association Water Research Centre Water Services Association of England and Wales The following bodies were also represented in the drafting of the standard, through subcommittees a
7、nd panels: The Association of the Laboratory Supply Industry British Agrochemicals Association Ltd. British Ceramic Research British Soft Drinks Association Ltd. GAMBICA (BEAMA) Ltd. Society of Chemical Industry Swimming Pool and Allied Trades Association Ltd. Amendments issued since publication Amd
8、. No.DateComments Licensed Copy: sheffieldun sheffieldun, na, Tue Dec 05 01:30:42 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6068-2.48:1995 BSI 07-1999i Contents Page Committees responsible Inside front cover National foreword ii Introduction 1 1Scope1 2Normative reference1 3Principle1 4Reagents1
9、 5Apparatus2 6Sampling and samples2 7Procedure2 8Calculation5 9Precision5 10Test report5 Annex A (informative) Bibliography6 Figure 1 Example of a distillation apparatus3 Table 1 Preparation of reference solutions4 Table 2 Precision data5 List of references Inside back cover Licensed Copy: sheffield
10、un sheffieldun, na, Tue Dec 05 01:30:42 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6068-2.48:1995 ii BSI 07-1999 National foreword This Section of BS 6068 has been prepared by Technical Committee EPC/44, and is identical with ISO 10359-2:1994 Water quality Determination of fluoride Part 2: Determ
11、ination of inorganically bound total fluoride after digestion and distillation. The international standard was prepared by Technical Committee 147, Water quality, of the International Organization for Standardization (ISO) with the active participation and approval of the UK. BS 6068 is being publis
12、hed in a series of Parts subdivided into Sections that will generally correspond to particular international standards. Sections are being, or will be, published in Parts 1 to 7, which, together with Part 0, are listed below. Part 0: Introduction; Part 1: Glossary; Part 2: Physical, chemical and bio
13、chemical methods; Part 3: Radiological methods; Part 4: Microbiological methods; Part 5: Biological methods; Part 6: Sampling; Part 7: Precision and accuracy; NOTEThe tests described in this Section of BS 6068 should only be carried out by suitably qualified persons with an appropriate level of biol
14、ogical expertise. Standard chemical procedures should be followed throughout. 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 con
15、fer immunity from legal obligations. Cross-reference International standardCorresponding British Standard ISO 5667-3:1994BS 6068 Water quality Section 6.3:1986 Guidance on the preservation and handling of samplesa a In preparation. The 1986 edition was identical with ISO 5667-3:1985. Summary of page
16、s 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 in the amendment table on the inside front cover.
17、Licensed Copy: sheffieldun sheffieldun, na, Tue Dec 05 01:30:42 GMT+00:00 2006, Uncontrolled Copy, (c) BSI ISO 10359-2:1994(E) BSI 07-19991 Introduction Fluoride ions occur in almost all ground and surface waters. Their concentration depends primarily on the hydrogeological conditions and is general
18、ly below 1 mg/l. Certain industrial waste waters may also contain fluoride ions in higher concentrations. The fluoride concentration is also dependant on the type and concentration of cations present at the same time in water, such as Ca2+, Mg2+, Al3+ or Fe3+, which may form sparingly soluble compou
19、nds with fluoride ions or complexes of low dissociation grade. In addition, stable boron-fluoride complexes exist. Several different methods are available for determining fluoride and the choice of method depends on the type of problem posed as follows. a) Direct measurement using fluoride ion selec
20、tive electrodes. This method is suitable for the determination of fluoride in drinking and surface water. It is included in ISO 10359-1. b) Determination of inorganically bound total fluoride using decomposition, distillation and potentiometric measurement. This method is included in this part of IS
21、O 10359. 1 Scope 1.1 Field of application This part of ISO 10359 specifies a method for the determination of inorganically bound total fluoride. The method is applicable to waste waters which are highly contaminated inorganically, with a fluoride ion concentration of more than 0,2 mg/l. 1.2 Interfer
22、ences Interferences caused by certain cations (see introduction) or boron, which may occur in the determination of fluoride, need to be eliminated by distillation. 2 Normative reference The following standard contains provisions which, through reference in this text, constitute provisions of this pa
23、rt of ISO 10359. At the time of publication, the edition indicated was valid. All standards are subject to revision, and parties to agreements based on this part of ISO 10359 are encouraged to investigate the possibility of applying the most recent edition of the standard indicated below. Members of
24、 IEC and ISO maintain registers of currently valid International Standards. ISO 5667-3:1994, Water quality Sampling Part 3: Guidance on the preservation and handling of samples. 3 Principle Evaporation of the water sample to dryness in an alkaline medium. Fusing of the residue with sodium hydroxide.
25、 Separation of the fluoride by steam distillation in the presence of a phosphoric acid/sulfuric acid mixture. Determination of the fluoride concentration in the distillate by means of a fluoride ionselective electrode (see ISO 10359-1). 4 Reagents During the analysis, use only reagents of recognized
26、 analytical grade and only distilled water or water of equivalent purity. 4.1 Hydrochloric acid (HCl), = 1,12 g/ml. 4.2 Phosphoric acid (H3PO4), = 1,71 g/ml. 4.3 Sulfuric acid (H2SO4), = 1,64 g/ml; 72,5 % (V/V). 4.4 Sodium hydroxide (NaOH), solid. 4.5 Sodium hydroxide solution c(NaOH) = 5 mol/l. Dis
27、solve cautiously 100 g 0,5 g of sodium hydroxide in water, cool and dilute to 500 ml. 4.6 Methyl red solution Dissolve 0,2 g of the sodium salt of methyl red (C15H14N3NaO2) in 100 ml of ethanol. 4.7 Total ionic strength adjustment buffer (TISAB). Add 58 g of sodium chloride (NaCl) and 57 ml of glaci
28、al acetic acid (CH3COOH) = 1,05 g/ml to 500 ml of water in a 1 litre beaker. Stir until dissolved. Add 150 ml of the sodium hydroxide solution (4.5) and 4 g of CDTA (trans-1,2-diaminocyclohexane-N,N,N,N- tetraacetic acid). Continue stirring until all the solids have dissolved and adjust the solution
29、 to pH 5,2 with sodium hydroxide solution using a pH-meter. Transfer to a 1 000 ml one-mark volumetric flask, make up to the mark with water and mix. The solution is stable for about 6 months, but do not use it if a precipitate forms. NOTE 1This solution is commercially available. 4.8 Fluoride, stoc
30、k solution, = 1 000 mg/l. Dry a portion of sodium fluoride (NaF) at 150 C for 4 h and cool in a desiccator. Dissolve 2,210 g 0,001 g of the dried material in water contained in a 1 000 ml one-mark volumetric flask. Make up to the mark with water and mix. Store the solution in a screw-capped polyethy
31、lene container. 4.8.1 Fluoride, working standard solution I, = 10 mg/l. Licensed Copy: sheffieldun sheffieldun, na, Tue Dec 05 01:30:42 GMT+00:00 2006, Uncontrolled Copy, (c) BSI ISO 10359-2:1994(E) 2 BSI 07-1999 Pipette 10 ml of the fluoride stock solution (4.8) into a 1 000 ml one-mark volumetric
32、flask. Make up to the mark with water and mix. 4.8.2 Fluoride, working standard solution II, = 5 mg/l. Pipette 5 ml of the stock solution (4.8) into a 1 000 ml one-mark volumetric flask and make up to the mark with water. 4.8.3 Fluoride, working standard solution III, = 1 mg/l. Pipette 100 ml of the
33、 working standard solution I (4.8.1) into a 1 000 ml one-mark volumetric flask and make up to the mark with water. 4.8.4 Fluoride, working standard solution IV, = 0,5 mg/l. Pipette 100 ml of the working standard solution II (4.8.2) into a 1 000 ml one-mark volumetric flask and make up to the mark wi
34、th water. 4.8.5 Fluoride, working standard solution V, = 0,2 mg/l. Pipette 20 ml of the working standard solution I (4.8.1) into a 1 000 ml one-mark volumetric flask and make up to the mark with water. All standard solutions are stored in plastics bottles and are usable for 1 month. 5 Apparatus Usua
35、l laboratory apparatus and 5.1 Meter, a millivoltmeter with an impedance of not less than 10127, capable of resolving potential differences of 0,1 mV or better. 5.2 Fluoride ion-selective electrode, which shall give stable readings. The e.m.f. response, using standard solutions, shall not be less th
36、an 55 mV per decade change in fluoride concentration at 25 C. 5.3 Reference electrode, either a calomel electrode, filled with saturated potassium chloride (KCl) solution, or a silver/silver chloride electrode shall be used. NOTE 2Single junction, sleeve type electrodes which reduce the liquid-liqui
37、d junction potential are preferable. 5.4 Measuring cells, of capacity 100 ml, made of polypropylene and fitted with a thermostatted jacket. 5.5 Water bath, capable of supplying water to the jacket of the measuring cell (5.4) at a temperature of 25 C 0,2 C. 5.6 Magnetic stirrer, with a PTFE-coated st
38、irring bar (PTFE = polytetrafluoroethylene). 5.7 Polyethylene beaker, of capacity 100 ml. 5.8 Nickel dishes, of a suitable size up to a capacity of 700 ml. 5.9 Crucibles, of 60 ml nominal capacity, made of glazed porcelain or nickel. 5.10 Distillation apparatus, (for example as shown in Figure 1) ma
39、de of borosilicate glass, suitable for steam distillation, consisting of a steam generating device, a 250 ml distillation flask, provided with a thermometer pocket with a 14/23 standard joint accomodating a distillation head provided with a splash head and dropping funnel and a coiled coolant tube c
40、ondenser (with a jacket length of at least 30 cm). The thermometer has a 14/23 standard joint and shall be suitable for a temperature range up to 200 C. 5.11 Heating device for the distillation flask, preferably an appropriately dimensioned heating jacket. 5.12 Round-bottomed flasks, of capacities 5
41、00 ml and 1 000 ml. 5.13 Volumetric flasks, of capacities 100 ml, 250 ml and 500 ml. 5.14 One-mark bulb pipettes, of capacities 10 ml, 20 ml, 25 ml and 50 ml. 5.15 Pipettes 5.16 Narrow-mouthed reagent bottles, of capacity 500 ml, made of brown glass. 6 Sampling and samples Samples shall be taken in
42、polyethylene bottles which have been washed thoroughly and rinsed with fluoride-free water. No preservative is normally necessary but perform the analysis as soon as possible, preferably within 3 days. For further information on sample preservation see ISO 5667-3. 7 Procedure 7.1 Evaporation and dec
43、omposition Transfer 500 ml of the water sample, which has been homogenized by shaking to a nickel dish (5.8). The fluoride concentration shall be between 0,2 mg/l and 2 000 mg/l. For higher fluoride concentrations, take a suitably smaller volume. Adjust the pH of the water sample to 11 to 12 by addi
44、ng sodium hydroxide solution (4.5) and concentrate by evaporation to a volume of approximately 30 ml. Transfer to a crucible (5.9) and carefully evaporate to dryness, avoiding overheating or splashing. Licensed Copy: sheffieldun sheffieldun, na, Tue Dec 05 01:30:42 GMT+00:00 2006, Uncontrolled Copy,
45、 (c) BSI ISO 10359-2:1994(E) BSI 07-19993 Cover the residue with 2 g of sodium hydroxide (4.4). Heat the contents of the crucible to 400 C to 500 C (dull red heat) and wait for 10 min. Cool and dissolve the melt in a small volume of water. 7.2 Distillation Transfer the dissolved melt (see 7.1) to a
46、distillation flask (see 5.10), ensuring that the total volume does not exceed 50 ml. Connect the flask to the rest of the distillation apparatus (5.10). Using the dropping funnel, carefully add 60 ml of sulfuric acid (4.3) and then 10 ml of phosphoric acid (4.2). Place a 500 ml volumetric flask cont
47、aining 20 ml of sodium hydroxide solution (4.5) under the condenser outlet. Submerge the outlet tube of the condenser in the solution. Switch on the steam generator and the heating jacket (5.11) for the distillation flask. When the contents of the flask begin to boil, introduce steam. Continue heati
48、ng until the contents of the distillation flask reach a temperature of 155 C. Regulate the heating to keep this temperature approximately constant. Adjust the steam supply for a distillation rate of approximately 10 ml/min. NOTE 3For larger series of analyses, it is advisable to replace the thermome
49、ter by a contact thermometer and to control the heating using a relay. Stop the distillation when the amount of distillate is approximately 450 ml. Rinse the condenser outlet tube inside and outside with a small volume of water. Neutralize the contents of the volumetric flask against methyl red (4.6) and make up to the mark with water. Figure 1 Example of a distillation apparatus Licensed Copy: sheffieldun sheffieldun, na, Tue Dec 05 01:30:42 GMT+00:00 2006, Uncontrolled Copy, (c) BSI ISO 10359-2:1994(E) 4 B