1、BRITISH STANDARD BS 6068-2.43: 1993 ISO 9964-2: 1993 Water quality Part 2: Physical, chemical and biochemical methods Section 2.43 Determination of sodium and potassium: determination of potassium by atomic absorption spectrometry UDC 614.777:556.114:543.42:546.32BS6068-2.43:1993 This British Standa
2、rd, having been prepared under the directionof the Environment andPollution Standards Policy Committee, was published underthe authority of the Standards Board and comes into effect on 15September1993 BSI 07-1999 The following BSI references relate to the work on this standard: Committee reference E
3、PC/44 Draft for comment 89/53614 DC ISBN 0 580 22550 X 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 repre
4、sented: 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 Che
6、mistry 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 Laborator
8、y) GAMBICA (BEAMA Ltd.) Ministry of Defence Swimming Pool and Allied Trades Association Ltd. Amendments issued since publication Amd. No. Date CommentsBS6068-2.43:1993 BSI 07-1999 i Contents Page Committees responsible Inside front cover National foreword ii 1 Scope 1 2 Normative references 1 3 Prin
9、ciple 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 coverBS6068-2.43:1993 ii BSI 07-1999 National foreword This Section of BS 6068, which has been prepared under the direction
10、of the Environment and Pollution Standards Policy Committee, is identical with ISO9964-2:1993 Water quality Determination of sodium and potassium Part 2: Determination of potassium by atomic absorption spectrometry. The international standard was prepared by Technical Committee 147, Water quality, o
11、f the 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
12、 Parts 1 to 7, which, together with Part 0, 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 60
13、68-2.42:1993 describes a method for determination of sodium 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. U
14、sers of 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 Guidanc
15、e on the 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, pages i and ii, pages1 to 4, an inside back cover and a back cover. This standard has been up
16、dated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover.BS 6068-2.43:1993 BSI 07-1999 1 1 Scope 1.1 Field of application This International Standard specifies a method for the determination of dissolved potassium by
17、 flame atomic absorption spectrometry (AAS). It is intended for the analysis of raw and drinking waters. The method is applicable to water samples with a mass concentration of potassium in the range from5mg/l to 50mg/l. This range can be extended to lower or higher limits if dilution factors are cho
18、sen which are different from the factor specified in clause 8. 1.2 Interferences The ions normally present in raw and drinking waters do not interfere with the determination of potassium by atomic absorption spectrometry. 2 Normative references The following standards contain provisions which, throu
19、gh reference in this text, 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 r
20、ecent editions of the 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 tec
21、hniques. 3 Principle Addition 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 of 766,5nm. 4 Reagents During the analysis, use on
22、ly reagents of recognized analytical grade and only deionized water or water of equivalent purity. 4.1 Hydrochloric acid, c(HCl) 11 mol/l, = 1,18g/ml. 4.2 Nitric acid, c(HNO 3 ) 16mol/l, = 1,41g/ml. 4.3 Caesium chloride, (CsCl), solution. Dissolve 25g of caesium chloride in a solution of50ml of hydr
23、ochloric acid (4.1) and 450ml of water, and dilute to 1litre 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 Potassium, stock solution In a 1000ml one-mark volumetric fl
24、ask, dissolve1,907g 0,005g of potassium chloride (previously dried for at least 1h at 140 C 10 C) 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 contains 1000mg of K. Alternatively, use a commercially av
25、ailable, readymade solution. 4.5 Potassium, standard solution Pipette 10ml of the potassium stock solution (4.4) into a 1000ml one-mark volumetric flask. Make up to the mark with water. The solution shall be prepared freshly when required. 1ml of this standard solution contains 104g of K. 5 Apparatu
26、s Ordinary laboratory apparatus and 5.1 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 potassium determination, and a compatible red-sensitive photomultiplier. A spect
27、ral bandwith of 0,3nm is recommended. All glassware shall be of borosilicate glass. Clean both glass and polyethylene ware by soaking in an aqueous solution of 10% (V/V) of nitric acid(4.2) followed by thorough rinsing with water. The apparatus should only be used for this method. 6 Sampling Collect
28、 samples in clean polyethylene 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
29、 pH of approximately 1. All samples, standards and blanks should contain the same concentration and the same type of acid.BS6068-2.43:1993 2 BSI 07-1999 7 Procedure 7.1 Preparation of test samples for presentation to the spectrometer 7.1.1 Filter samples containing particulate matter through an acid
30、-washed filter of pore size 0,454m 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
31、 from suspension by using a centrifuge. 7.1.2 Take a number of 100ml one-mark volumetric flasks according to the number of samples being analysed. To each of these flasks, add 10ml of the caesium chloride solution (4.3). 7.1.3 Pipette, 10ml of the sample into each of these caesium chloride solutions
32、, and make up to the mark with water. If the concentration of the test solution is not in the optimum range of 0,1mg/l to1,0mg/l of K, adjust the volume of the sample appropriately. 7.2 Preparation of the set of calibration solutions Add 10ml of caesium chloride solution to each of a series of 100ml
33、 one-mark volumetric flasks. Pipette0ml; 1,0ml; 2,0ml; 4,0ml; 6,0ml and10,0ml of the potassium standard solution(4.5) into the series flasks and make up each flask to the mark with water. The calibration solutions will have the concentrations 0mg/l; 0,1mg/l; 0,2mg/l; 0,4mg/l; 0,6mg/l and 1,0mg/l of
34、K, respectively. 7.3 Calibration and determination 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). Adj
35、ust the response of the instrument to zero absorbance with water. 7.3.2 Aspirate the calibration solutions (7.2) with an aspiration of water between each. Measure the absorbance at 766,5nm. Prepare a calibration graph by plotting the respective absorbance readings on the ordinate against the mass co
36、ncentrations of potassium on the abscissa. Calculate from the graph the slope, b, in litres per milligram. NOTE 4The calibration graph is normally linear for the concentration range 0,1mg/l to 1,0mg/l. 7.3.3 Aspirate the test samples (7.1), with an aspiration of water between each, and determine the
37、 absorbance. 7.3.4 Carry out a blank determination 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. every 10 samples). 8 Calculation and expression of resu
38、lts 8.1 Use of calibration graph Read the concentrations of potassium in the test solutions from the calibration graph (see 7.3.2). From these values, calculate the potassium concentration of the test sample, taking into account the volume of test sample taken (normally 10ml) and the total volume of
39、 the volumetric flask(100ml). 8.2 Method of calculation If the calibration graph is linear, calculate the mass concentration of potassium, K , in the sample, in milligrams per litre, using the equation where If required, calculate the amount-of-substance concentration, c K , in millimoles per litre,
40、 using the equation If the calibration curve is not linear, proceed as described in 8.1. 8.3 Precision An interlaboratory trial, carried out in autumn1991, using this method, produced the results given in Table 1. . . . (1) A is the absorbance of the sample; A 0 is the absorbance of the blank; V m i
41、s the volume, in millilitres, of the test portion (normally 10ml); V p is the volume, in millilitres, of the volumetric flask (100ml); b is the slope of the calibration curve, in litres per milligram. . . . (2) K AA 0 ()V m V p b - = c K K 39,1 - =BS 6068-2.43:1993 BSI 07-1999 3 Table 1 Precision da
42、ta 9 Test report The test report shall include the following information: 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 clause 8; d) any deviation from this method or any other circum
43、stances which may have influenced the results. Sample a l n n a r VC r R VC R % mg/l mg/l % mg/l % A 10 27 10 0,99 0,058 1 5,9 0,041 1 4,2 B 10 30 0 5,72 0,227 9 4,0 0,096 1 1,7 C 10 30 0 6,71 0,239 7 3,6 0,138 7 2,1 l is the number of laboratories r is the repeatability standard deviation n is the
44、number of values VC r is the repeatability variation coefficient n a 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 blankBS6068-2.43:1993 BSI 07-199
45、9 List of references See national foreword.BS 6068-2.43: 1993 ISO9964-2: 1993 BSI 389 Chiswick High Road London W4 4AL BSIBritishStandardsInstitution BSI is the independent national body responsible for preparing BritishStandards. It presents the UK view on standards in Europe and at the internation
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