BS 6068-2 42-1993 Water quality - Physical chemical and biochemical methods - Determination of sodium and potassium determination of sodium by atomic absorption spectrometry《水质 第2部.pdf

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1、BRITISH STANDARD BS 6068-2.42: 1993 ISO 9964-1: 1993 Water quality Part 2: Physical, chemical and biochemical methods Section 2.42 Determination of sodium and potassium: determination of sodium by atomic absorption spectrometry UDC 614.777:556.114:543.42:546.33BS 6068-2.42:1993 This British Standard

2、, having been prepared under the directionof the Environment andPollution Standards Policy Committee, was published underthe authority of the Standards Board and comes intoeffect on 15 September 1993 BSI 06-1999 The following BSI references relate to the work on this standard: Committee reference EP

3、C/44 Draft for comment 89 53614 DC ISBN 0 580 22549 6 Committees responsible for this British Standard The preparation of this British Standard was entrusted by the Environment and Pollution Standards Policy Committee (EPC/-) to Technical Committee EPC/44, upon which the following bodies were repres

4、ented: Association of Consulting Scientists British Association for Chemical Specialities British Gas plc Chemical Industries Association Convention of Scottish Local Authorities Department of the Environment for Northern Ireland Department of the Environment (Water Directorate) Department of Trade

5、and Industry (Laboratory of the Government Chemist) Electricity Association Industrial Water Society Institute of Gas Engineers Institution of Water and Environmental Management Institution of Water Officers National Rivers Authority Royal Institute of Public Health and Hygiene Royal Society of Chem

6、istry Scottish Association of Directors of Water and Sewerage Services Soap and Detergent Industry Association Society of Chemical Industry Water Companies Association Water Research Centre Water Services Association of England and Wales The following bodies were also represented in the drafting of

7、the standard, through subcommittees and panels: British Agrochemicals Association Ltd. British Ceramic Research Ltd. British Laboratory Ware Association (The Association of the Laboratory Supply Industry) British Soft Drinks Association Ltd. Department of Trade and Industry (Warren Spring Laboratory

8、) GAMBICA (BEAMA Ltd.) Ministry of Defence Swimming Pool and Allied Trades Association Ltd. Amendments issued since publication Amd. No. Date CommentsBS6068-2.42:1993 BSI 06-1999 i Contents Page Committees responsible Inside front cover National foreword ii 1 Scope 1 2 Normative references 1 3 Princ

9、iple 1 4 Reagents 1 5 Apparatus 1 6 Sampling 1 7 Procedure 2 8 Calculation and expression of results 2 9 Test report 3 Table 1 Precision data 3 List of references Inside back coverBS 6068-2.42:1993 ii BSI 06-1999 National foreword This Section of BS6068, which has been prepared under the direction o

10、f the Environment and Pollution Standards Policy Committee is identical with ISO9964-1:1993 Water quality Determination of sodium and potassium Part 1: Determination of sodium by atomic absorption spectrometry. The international standard was prepared by Technical Committee147, Water quality, of the

11、International Organization for Standardization (ISO) with the active participation and approval of the UK. BS 6068 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 Parts

12、1 to7, which, together with Part0, are listed below. Part 0: Introduction; Part 1: Glossary; Part 2: Physical, chemical and biochemical methods; Part 3: Radiological methods; Part 4: Microbiological methods; Part 5: Biological methods; Part 6: Sampling; Part 7: Precision and accuracy. BS 6068-2.43:1

13、993 describes a method for determination of potassium by atomic absorption spectrometry and BS6068-2.44:1993 describes a method for determination of sodium and potassium by flame emission spectrometry. A British Standard does not purport to include all the necessary provisions of a contract. Users o

14、f British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Cross-references International standard Corresponding British Standard BS 6068 Water quality ISO 5667-1:1980 Section 6.1:1981 Guidance on t

15、he design of sampling programmes (Identical) ISO 5667-2:1991 Section 6.2:1991 Guidance on sampling techniques (Identical) Summary of pages This document comprises a front cover, an inside front cover, pagesi andii, pages1 to4, an inside back cover and a back cover. This standard has been updated (se

16、e copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover.BS6068-2.42:1993 BSI 06-1999 1 1 Scope 1.1 Field of application This International Standard specifies a method for the determination of dissolved sodium by flame atomic

17、 absorption spectrometry (AAS). It is intended for the analysis of raw and drinking water. The method is applicable to water samples with a mass concentration of sodium in the range from5mg/l to50mg/l. This range can be extended to lower or higher limits if dilution factors are chosen which are diff

18、erent from the factor specified in clause8. 1.2 Interferences The ions normally present in raw and drinking waters do not interfere with the determination of sodium by atomic absorption spectrometry. 2 Normative references The following standards contain provisions which, through reference in this t

19、ext, constitute provisions of this part of ISO9964. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this part of ISO9964 are encouraged to investigate the possibility of applying the most recent editions of the

20、standards indicated below. Members of IEC and ISO maintain registers of currently valid International Standards. ISO 5667-1:1980, Water quality Sampling Part1: Guidance on the design of sampling programmes. ISO 5667-2:1991, Water quality Sampling Part2: Guidance on sampling techniques. 3 Principle A

21、ddition of caesium chloride solution to the sample as an ionization suppressant. Aspiration of the sample directly into the air/acetylene flame of an atomic absorption spectrometer. Measurement of the absorbance at a wavelength of589,0nm. 4 Reagents During the analysis, use only reagents of recogniz

22、ed analytical grade and only deionized water or water of equivalent purity. 4.1 Hydrochloric acid, c(HCl) 11 mol/l, = 1,18 g/ml. 4.2 Nitric acid, c(HNO 3 ) 16 mol/l, = 1,41 g/ml. 4.3 Caesium chloride, (CsCl), solution. Dissolve25g of caesium chloride in a solution of50ml of hydrochloric acid (4.1) a

23、nd450ml of water, and dilute to1litre with water in a one-mark volumetric flask. One litre of this solution contains approximately20g of Cs. NOTE 1Nitric acid (4.2) may be used instead of hydrochloric acid (4.1). 4.4 Sodium, stock solution In a 1000ml one-mark volumetric flask, dissolve2,542g 0,005g

24、 of sodium chloride (previously dried for at least1h at140C 10C) in water and make up to the mark. Store the solution, which is stable for at least6months, in a polyethylene bottle. One litre of this solution contains1000mg of Na. Alternatively, use a commercially available, readymade solution. 4.5

25、Sodium, standard solution Pipette10ml of the sodium stock solution (4.4) into a1000ml one-mark volumetric flask. Make up to the mark with water. The solution shall be prepared freshly when required. 1 ml of this standard solution contains 10 4g of Na. 5 Apparatus Ordinary laboratory apparatus and 5.

26、1 Atomic absorption spectrometer, set up and operated according to the manufacturers instructions, it is equipped with a burner for an air/acetylene flame, a hollow cathode lamp for sodium determination, and a compatible red-sensitive photomultiplier. A spectral bandwith of 0,3 nm is recommended. 5.

27、2 Glassware of borosilicate glass, and polyethylene ware. Clean both glass and polyethylene ware by soaking in an aqueous solution of10% (V/V) of nitricacid(4.2) followed by thorough rinsing with water. The apparatus should only be used for this method. 6 Sampling Collect samples in clean polyethyle

28、ne bottles (seeISO5667-1 and ISO5667-2). Sample preservation by acidification is not generally necessary. NOTE 2If other metal analyses are to be carried out on the samples, the samples can be preserved by addition of hydrochloric acid (4.1) or nitric acid (4.2) to give a pH of approximately1. All s

29、amples, standards and blanks should contain the same concentration and the same type of acid.BS 6068-2.42:1993 2 BSI 06-1999 7 Procedure 7.1 Preparation of test samples for presentation to the spectrometer 7.1.1 Filter samples containing particulate matter through an acid-washed filter of pore size0

30、,454m to prevent clogging of the nebulizer and burner systems. (The acid used for washing the filter should have the same concentration and be of the same type as the acid used in the sample preparation.) NOTE 3Instead of filtration, the particulate matter may be removed from suspension by using a c

31、entrifuge. 7.1.2 Take a number of100ml one-mark volumetric flasks according to the number of samples being analysed. To each of these flasks, add10ml of the caesium chloride solution (4.3). 7.1.3 Pipette,2ml of the sample into each of these caesium chloride solutions, and make up to the mark with wa

32、ter. If the concentration of the test solution is not in the optimum range of0,1mg/l to1,0mg/l of Na, adjust the volume of the sample appropriately. 7.2 Preparation of the set of calibration solutions Add 10 ml of caesium chloride solution to each of a series of100ml one-mark volumetric flasks. Pipe

33、tte0ml;1,0ml;2,0ml;4,0ml;6,0ml and10,0ml of the sodium standard solution (4.5) into the series flasks and make up each flask to the mark with water. The calibration solutions will have the concentrations0mg/l;0,1mg/l; 0,2mg/l; 0,4mg/l; 0,6mg/l and 1,0mg/l of Na, respectively. 7.3 Calibration and det

34、ermination 7.3.1 Set up the spectrometer according to the manufacturers instructions by aspirating a calibration solution (7.2). Optimize the aspiration and flame conditions (aspiration rate, nature of the flame, position of the optical beam in the flame). Adjust the response of the instrument to ze

35、ro absorbance with water. 7.3.2 Aspirate the calibration solutions (7.2) with an aspiration of water between each. Measure the absorbance at589,0nm. Prepare a calibration graph by plotting the respective absorbance readings on the ordinate against the mass concentrations of sodium on the abscissa. C

36、alculate from the graph the slope, b, in litres per milligram. NOTE 4The calibration graph is normally linear for the concentration range0,1mg/l to1,0mg/l. 7.3.3 Aspirate the test samples (7.1), with an aspiration of water between each, and determine the absorbance. 7.3.4 Carry out a blank determina

37、tion with each batch of samples by applying the same procedure and using water instead of the sample. NOTE 5It is good practice to check the slope of the calibration graph at regular intervals (e.g. every10samples). 8 Calculation and expression of results 8.1 Use of calibration graph Read the concen

38、trations of sodium in the test solutions from the calibration graph (see7.3.2). From these values, calculate the sodium concentration of the test sample, taking into account the volume of test sample taken (normally2ml) and the total volume of the volumetric flask (100ml). 8.2 Method of calculation

39、If the calibration graph is linear, calculate the mass concentration of sodium, Na , in the sample, in milligrams per litre, using the equation where If required, calculate the amount-of-substance concentration, c Na , in millimoles per litre, using the equation If the calibration curve is not linea

40、r, proceed as described in8.1. 8.3 Precision An interlaboratory trial, carried out in autumn1991, using this method, produced the results given inTable 1. .(1) A is the absorbance of the sample; A 0 is the absorbance of the blank; V m is the volume, in millilitres, of the test portion (normally 2 ml

41、); V p is the volume, in millilitres, of the volumetric flask (100 ml); b is the slope of the calibration curve, in litres per milligram. .(2) Na AA 0 ()V m V p b - = c Na Na 23,0 - =BS6068-2.42:1993 BSI 06-1999 3 Table 1 Precision data 9 Test report The test report shall include the following infor

42、mation: a) a reference to this International Standard; b) precise identification of the water sample; c) the results and the method of expression used, in accordance with clause8; d) any deviation from this method or any other circumstances which may have influenced the results. Sample a l n n a B r

43、 VC r B R VC R % mg/l mg/l % mg/l % A 8 21 13 6,11 0,211 4 3,5 0,112 4 1,8 B 8 24 0 65,2 2,503 4 3,8 0,588 1 0,9 C 8 21 13 294 11,071 3,8 2,320 0,8 l is the number of laboratories r is the repeatability standard deviation n is the number of values VC r is the repeatability variation coefficient n a

44、is the percentage of outliers R is the reproducibility standard deviation is the mean value VC R is the reproducibility variation coefficient a A: drinking water B: surface water C: waste water x x4 blankBS6068-2.42:1993 BSI 06-1999 List of references See national foreword.BS 6068-2.42: 1993 ISO 996

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