BS EN ISO 6878-2004 Water quality - Determination of phosphorus - Ammonium molybdate spectrometric method《水质 磷的测定 钼酸铵的光谱测定法》.pdf

1、BRITISH STANDARD BS EN ISO 6878:2004 BS 6068-2.28:2004 Water quality Determination of phosphorus Ammonium molybdate spectrometric method The European Standard EN ISO 6878:2004 has the status of a British Standard ICS 13.060.50 BS EN ISO 6878:2004 This British Standard was published under the authori

2、ty of the Standards Policy and Strategy Committee on 14 June 2004 BSI 14 June 2004 ISBN 0 580 43933 X National foreword This British Standard is the official English language version of EN ISO 6878:2004. It is identical with ISO 6878:2004. It supersedes BS EN 1189:1997 which is withdrawn. The UK par

3、ticipation in its preparation was entrusted by Technical Committee EH/3, Water quality, to Subcommittee EH/3/2, Physical, chemical and biochemical methods, which has the responsibility to: A list of organizations represented on this subcommittee can be obtained on request to its secretary. Cross-ref

4、erences The British Standards which implement international or European publications referred to in this document may be found in the BSI Catalogue under the section entitled “International Standards Correspondence Index”, or by using the “Search” facility of the BSI Electronic Catalogue or of Briti

5、sh Standards Online. This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. aid enquirers to understand the text; present

6、 to the responsible European committee any enquiries on the interpretation, or proposals for change, and keep the UK interests informed; monitor related international and European developments and promulgate them in the UK. Summary of pages This document comprises a front cover, an inside front cove

7、r, the EN ISO title page, the EN ISO foreword page, the ISO title page, pages ii to v, a blank page, pages 1 to 21 and a back cover. The BSI copyright notice displayed in this document indicates when the document was last issued. Amendments issued since publication Amd. No. Date CommentsEUROPEANSTAN

8、DARD NORMEEUROPENNE EUROPISCHENORM ENISO6878 June2004 ICS13.060.50 SupersedesEN1189:1996 Englishversion WaterqualityDeterminationofphosphorusAmmonium molybdatespectrometricmethod(ISO6878:2004) QualitdeleauDosageduphosphoreMthode spectromtriqueaumolybdatedammonium(ISO 6878:2004) ThisEuropeanStandardw

9、asapprovedbyCENon21May2004. CENmembersareboundtocomplywiththeCEN/CENELECInternalRegulationswhichstipulatetheconditionsforgivingthisEurope an Standardthestatusofanationalstandardwithoutanyalteration.Uptodatelistsandbibliographicalreferencesconcernings uchnational standardsmaybeobtainedonapplicationto

10、theCentralSecretariatortoanyCENmember. ThisEuropeanStandardexistsinthreeofficialversions(English,French,German).Aversioninanyotherlanguagemadebytra nslation undertheresponsibilityofaCENmemberintoitsownlanguageandnotifiedtotheCentralSecretariathasthesamestatusast heofficial versions. CENmembersarethe

11、nationalstandardsbodiesofAustria,Belgium,Cyprus,CzechRepublic,Denmark,Estonia,Finland,France, Germany,Greece,Hungary,Iceland,Ireland,Italy,Latvia,Lithuania,Luxembourg,Malta,Netherlands,Norway,Poland,Portugal, Slovakia, Slovenia,Spain,Sweden,SwitzerlandandUnitedKingdom. EUROPEANCOMMITTEEFORSTANDARDIZ

12、ATION COMITEUROPENDENORMALISATION EUROPISCHESKOMITEEFRNORMUNG ManagementCentre:ruedeStassart,36B1050Brussels 2004CEN Allrightsofexploitationinanyformandbyanymeansreserved worldwideforCENnationalMembers. Ref.No.ENISO6878:2004:E Foreword This document (EN ISO 6878:2004) has been prepared by Technical

13、Committee ISO/TC 147 “Water quality“ in collaboration with Technical Committee CEN/TC 230 “Water analysis“, the secretariat of which is held by DIN. 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

14、 December 2004, and conflicting national standards shall be withdrawn at the latest by December 2004. This document supersedes EN 1189:1996. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standar

15、d: Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom. Endorsement notice The te

16、xt of ISO 6878:2004 has been approved by CEN as EN ISO 6878:2004 without any modifications. ENISO6878:2004 Reference number ISO 6878:2004(E)INTERNATIONAL STANDARD ISO 6878 Second edition 2004-06-01 Water quality Determination of phosphorus Ammonium molybdate spectrometric method Qualit de leau Dosag

17、e du phosphore Mthode spectromtrique au molybdate dammonium ENISO6878:2004 ii ENISO6878:2004 iiiContents Page Foreword iv Introduction v 1 Scope 1 2 Interferences 1 3 Principle . 1 4 Determination of orthophosphate . 2 5 Determination of orthophosphate after solvent extraction 7 6 Determination of h

18、ydrolysable phosphate and orthophosphate. 9 7 Determination of total phosphorus after peroxodisulfate oxidation . 11 8 Determination of total phosphorus after nitric acid-sulfuric acid digestion 14 Annex A (informative) Interferences. 17 Annex B (informative) Precision data. 19 Bibliography . 21 ENI

19、SO6878:2004iv Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject

20、 for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC)

21、on all matters of electrotechnical standardization. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2. The main task of technical committees is to prepare International Standards. Draft International Standards adopted by the technical committees

22、 are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be hel

23、d responsible for identifying any or all such patent rights. ISO 6878 was prepared by Technical Committee ISO/TC 147, Water quality, Subcommittee SC 2, Physical, chemical and biochemical methods. This second edition cancels and replaces the first edition (ISO 6878:1998), which has been technically r

24、evised. ENISO6878:2004 vIntroduction This International Standard specifies the determination of different forms of phosphorus compounds present in ground, surface and waste waters in various concentrations in the dissolved and undissolved state. The user should be aware that particular problems coul

25、d require the specification of additional marginal conditions. ENISO6878:2004 1Water quality Determination of phosphorus Ammonium molybdate spectrometric method WARNING Persons using this International Standard should be familiar with normal laboratory practice. This International Standard does not

26、purport to address all of the safety problems, if any, associated with its use. It is the responsibility of the user to establish appropriate safety and health practices and to ensure compliance with any national regulatory conditions. It is absolutely essential that tests conducted according to thi

27、s International Standard be carried out by suitably qualified staff. Molybdate and antimony waste solutions should be disposed of properly. 1 Scope This International Standard specifies methods for the determination of orthophosphate (see Clause 4); orthophosphate after solvent extraction (see Claus

28、e 5); hydrolysable phosphate plus orthophosphate (see Clause 6); total phosphorus after decomposition (see Clauses 7 and 8). The methods are applicable to all kinds of water including seawater and effluents. Phosphorus concentrations within the range of 0,005 mg/l to 0,8 mg/l may be determined in su

29、ch samples without dilution. A solvent extraction procedure allows smaller phosphorus concentrations to be determined with a detection limit of about 0,000 5 mg/l. 2 Interferences See Annex A for some known interferences. There may be others and it is recommended to verify whether any such interfere

30、nces exist and take action to eliminate them. 3 Principle Reaction of orthophosphate ions with an acid solution containing molybdate and antimony ions to form an antimony phosphomolybdate complex. Reduction of the complex with ascorbic acid to form a strongly coloured molybdenum blue complex. Measur

31、ement of the absorbance of this complex to determine the concentration of orthophosphate present. Polyphosphate and some organophosphorus compounds are determined if converted to molybdate reactive orthophosphate formed by sulfuric acid hydrolysis. Many organophosphorus compounds are converted to or

32、thophosphate by mineralization with peroxodisulfate. Nitric acid-sulfuric acid mineralization is used if a more vigorous treatment is required. ENISO6878:20042 4 Determination of orthophosphate 4.1 Reagents During the analysis, use only reagents of recognized analytical grade and only water having a

33、 phosphate content that is negligible compared with the lowest concentration to be determined in the samples. For low phosphate contents, double-distilled water from an all-glass apparatus is recommended. 4.1.1 Sulfuric acid solution, c(H 2 SO 4 ) 9 mol/l. Add 500 ml 5 ml of water to a 2 l beaker. C

34、autiously add, with continuous stirring and cooling, 500 ml 5 ml of sulfuric acid, = 1,84 g/ml. Mix well and allow the solution to cool to room temperature. 4.1.2 Sulfuric acid solution, c(H 2 SO 4 ) 4,5 mol/l. Add 500 ml 5 ml of water to a 2 l beaker. Cautiously add, with continuous stirring and co

35、oling, 500 ml 5 ml of sulfuric acid (4.1.1). Mix well and allow to cool to room temperature. 4.1.3 Sulfuric acid solution, c(H 2 SO 4 ) 2 mol/l. Add 300 ml 3 ml of water to a 1 l beaker. Cautiously add 110 ml 2 ml of sulfuric acid solution (4.1.1), with continuous stirring and cooling. In a measurin

36、g flask, dilute to 500 ml 2 ml with water and mix well. 4.1.4 Sodium hydroxide solution, c(NaOH) = 2 mol/l. Dissolve 80 g 1 g of sodium hydroxide pellets in water, cool and dilute to 1 l with water. 4.1.5 Ascorbic acid solution, = 100 g/l. Dissolve 10 g 0,5 g of ascorbic acid (C 6 H 8 O 6 ) in 100 m

37、l 5 ml water. NOTE The solution is stable for 2 weeks if stored in an amber glass bottle in a refrigerator and can be used as long as it remains colourless. 4.1.6 Acid molybdate, Solution I. Dissolve 13 g 0,5 g of ammonium heptamolybdate tetrahydrate (NH 4 ) 6 Mo 7 O 24 4H 2 O in 100 ml 5 ml of wate

38、r. Dissolve 0,35 g 0,05 g of antimony potassium tartrate hemihydrate K(SbO)C 4 H 4 O 6 H 2 O in 100 ml 5 ml of water. Add the molybdate solution to 300 ml 5 ml of sulfuric acid (4.1.1) with continuous stirring. Add the tartrate solution and mix well. NOTE The reagent is stable for at least 2 months

39、if stored in an amber glass bottle. 4.1.7 Acid molybdate, Solution II. Cautiously add 230 ml 0,5 ml of sulfuric acid (4.1.1) to 70 ml 5 ml of water, cool. Dissolve 13 g 0,5 g of ammonium heptamolybdate tetrahydrate (NH 4 ) 6 Mo 7 O 24 4H 2 O in 100 ml 5 ml of water. Add to the acid solution and mix

40、well. Dissolve 0,35 g 0,05 g of antimony potassium tartrate hemihydrate K(SbO)C 4 H 4 O 6 H 2 O in 100 ml 5 ml of water. Add to the molybdate-acid solution and mix well. This reagent is used when the sample is acidified with sulfuric acid (4.1.2) (see also Clauses 6, 7 and 8). NOTE The reagent is st

41、able for at least 2 months if stored in an amber glass bottle. ENISO6878:2004 34.1.8 Turbidity-colour compensation solution. On a volume/volume basis, mix two parts of sulfuric acid (4.1.2) and one part of ascorbic acid (4.1.5). NOTE The reagent is stable for several weeks if stored in an amber glas

42、s bottle in a refrigerator. 4.1.9 Sodium thiosulfate pentahydrate solution, = 12,0 g/l. Dissolve 1,20 g 0,05 g of sodium thiosulfate pentahydrate (Na 2 S 2 O 3 5H 2 O) in 100 ml 5 ml of water. Add 0,05 g 0,005 g of anhydrous sodium carbonate (Na 2 CO 3 ) as preservative. NOTE The reagent is stable f

43、or at least 4 weeks if stored in an amber glass bottle. 4.1.10 Orthophosphate stock standard solution, P = 50 mg/l. Dry a few grams of potassium dihydrogen phosphate to constant mass at 105 C. Dissolve 0,219 7 g 0,000 2 g of KH 2 PO 4in about 800 ml 10 ml of water in a 1 000 ml volumetric flask. Add

44、 10 ml 0,5 ml of sulfuric acid (4.1.2) and make up to the mark with water. Alternatively, use a commercially available stock solution. The solution is stable for at least 3 months if stored in a well stoppered glass bottle. Refrigeration to about 4 C is recommended. 4.1.11 Orthophosphate standard so

45、lution, P= 2 mg/l. Pipette 20 ml 0,01 ml of orthophosphate stock standard solution (4.1.10) into a 500 ml volumetric flask. Make up to the mark with water and mix well. Prepare and use this solution each day as required. NOTE 1 ml of this standard solution contains 2 g P. 4.1.12 Hydrochloric acid, (

46、HCl) = 1,19 g/ml. 4.1.13 Hydrochloric acid, c(HCl) = 2,5 mol/l. Cautiously add 200 ml 10 ml of hydrochloric acid (4.1.12) to 500 ml 10 ml of water. Mix and cool to room temperature. Make up to 1 000 ml with water. 4.2 Apparatus 4.2.1 Spectrometer, “prism”- or “grating-type” or filter type, capable o

47、f accepting optical cells of thickness 10 mm to 50 mm. The spectrometer chosen shall be suitable for measuring absorbance in the visible and near infra-red regions of the spectrum. The most sensitive wavelength is 880 nm, but if a loss of sensitivity can be accepted, absorbance may be measured at 70

48、0 nm. NOTE The detection limit of the method is lower if a spectrometer capable of accepting 100 mm optical cells is available. 4.2.2 Filter assembly, to hold a membrane filter of nominal pore size 0,45 m. 4.2.3 Glassware. Before use, wash all glassware, for example with hydrochloric acid (4.1.13), at approximately 40 C to 50 C and rinse thoroughly with water. Detergents containing phosphate shall not be used. ENISO6878:20044 Preferably the