1、BRITISH STANDARD BS EN 25663:1993 ISO 5663:1984 Water quality Determination of Kjeldahl nitrogen Method after mineralization with selenium The European Standard EN 25663:1993 has the status of a British Standard UDC 628.1/.3:620.1:546.17BSEN25663:1993 This British Standard, having been prepared unde
2、r the directionof the Environment andPollution Standards Policy Committee, was published underthe authority of the Standards Board and comesintoeffect on 15November1993 BSI 11-1999 The following BSI references relate to the work on this standard: Committee reference EPC/44 Draft announced in BSINews
3、 August 1992 ISBN 0 580 21207 6 Cooperating organizations The European Committee for Standardization (CEN), under whose supervision this European Standard was prepared, comprises the national standards organizations of the following countries: Austria Oesterreichisches Normungsinstitut Belgium Insti
4、tut belge de normalisation Denmark Dansk Standardiseringsraad Finland Suomen Standardisoimisliito, r.y. France Association franaise de normalisation Germany Deutsches Institut fr Normung e.V. Greece Hellenic Organization for Standardization Iceland Technological Institute of Iceland Ireland National
5、 Standards Authority of Ireland Italy Ente Nazionale Italiano di Unificazione Luxembourg Inspection du Travail et des Mines Netherlands Nederlands Normalisatie-instituut Norway Norges Standardiseringsforbund Portugal Instituto Portugus da Qualidade Spain Asociacin Espaola de Normalizacin y Certifica
6、cin Sweden Standardiseringskommissionen i Sverige Switzerland Association suisse de normalisation United Kingdom British Standards Institution Amendments issued since publication Amd. No. Date CommentsBSEN25663:1993 BSI 11-1999 i Contents Page Cooperating organizations Inside front cover National fo
7、reword ii Foreword 2 Text of EN 25663 3 National annex NA (informative) Committees responsible Inside back cover National annex NB (informative) Cross-reference Inside back coverBSEN25663:1993 ii BSI 11-1999 National foreword This British Standard has been prepared under the direction of the Environ
8、ment and Pollution Standards Policy Committee and is the English language version of EN 25663 Water quality Determination of Kjeldahl nitrogen Method after mineralization with selenium published by the European Committee for Standardization (CEN), which endorses ISO 5663:1984 published by the Intern
9、ational Organization for Standardization (ISO). 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 confer immunity from legal obliga
10、tions. Summary of pages This document comprises a front cover, an inside front cover, pagesi andii, theEN title page, pages2 to6, 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 amendme
11、nt table on the inside front cover.EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN25663 September1993 UDC 628.1/.3:620.1:546.17 Descriptors: Water tests, potable water, sewage, quality, water pollution, chemical analysis, determination of content, nitrogen, Kjeldahl method, mineralization, sele
12、nium English version Water quality Determination of Kjeldahl nitrogen Method after mineralization with selenium (ISO 5663:1984) Qualit de leau Dosage de lazote Kjeldahl Mthode aprs minralisation slnium (ISO5663:1984) Wasserbeschaffenheit Bestimmung von Kjeldahl-Stickstoff Verfahren nach Aufschlu mit
13、 Selen (ISO 5663:1984) This European Standard was approved by CEN on 1993-09-10. CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration. Up-to-date lists and b
14、ibliographical references concerning such national standards may be obtained on application to the Central Secretariat or to any CEN member. This European Standard exists in three official versions (English, French, German). A version in any other language made by translation under the responsibilit
15、y of a CEN member into its own language and notified to the Central Secretariat has the same status as the official versions. CEN members are the national standards bodies of Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portug
16、al, Spain, Sweden, Switzerland and United Kingdom. CEN European Committee for Standardization Comit Europen de Normalisation Europisches Komitee fr Normung Central Secretariat: rue de Stassart 36, B-1050 Brussels 1993 Copyright reserved to CEN members Ref. No. EN 25663:1993 EEN25663:1993 2 BSI 11-19
17、99 Foreword This European Standard has been taken over by CEN/TC 230 “Water quality” from the work of ISO/TC 147 “Water quality” of the International Organization for Standardization (ISO). CEN/TC 230 decided to submit this Final Draft to the CEN members for voting by Unique Acceptance Procedure (UA
18、P). The result of the Unique Acceptance Procedure was positive. 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 March 1994, and conflicting national standards shall be withdrawn at the latest by M
19、arch 1994. In accordance with the CEN/CENELEC Internal Regulations, the following countries are bound to implement this European Standard: Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and U
20、nited Kingdom. Contents Page Foreword 2 1 Scope and field of application 3 2 Reference 3 3 Definition 3 4 Principle 3 5 Reagents 3 6 Apparatus 4 7 Sampling and samples 4 8 Procedure 4 9 Expression of results 5 10 Interferences 5 11 Notes on procedure 6 12 Test report 6 Table 1 Selection of test port
21、ion 4 Table 2 Repeatability standard deviations 6EN25663:1993 BSI 11-1999 3 1 Scope and field of application 1.1 Substance determined This International Standard specifies a method for the determination of nitrogen by a Kjeldahl-type method. Only trivalent negative nitrogen is determined. Organic ni
22、trogen in the form of azide, azine, azo, hydrazone, nitrite, nitro, nitroso, oxime or semicarbazone is not determined quantitatively. Nitrogen may be incompletely recovered from heterocyclic nitrogen compounds. 1.2 Type of sample This method is applicable to the analysis of raw, potable and waste wa
23、ters. 1.3 Range A Kjeldahl nitrogen content, N , of up to 10 mg, in the test portion may be determined. Using a 10 ml test portion, this corresponds to a sample concentration of up to N= 1 000 mg/l. 1.4 Limit of detection A practically determined (4 degrees of freedom) limit of detection, using a 10
24、0 ml test portion, is N =1 mg/l. 1.5 Sensitivity Using a 100 ml test portion, 1,0 ml of 0,02 mol/l hydrochloric acid is equivalent to N= 2,8 mg/l. 2 Reference ISO 7150-1, Water quality Determination of ammonium Part 1: Manual spectrometric method. 3 Definition For the purpose of this International S
25、tandard, the following definition applies: Kjeldahl nitrogen the content of organic nitrogen and ammoniacal nitrogen in a sample determined after mineralization it does not include nitrate and nitrite nitrogen, and does not necessarily include all organically bound nitrogen 4 Principle Mineralizatio
26、n of the sample to form ammonium sulfate, from which ammonia is liberated and distilled for subsequent determination by titration. Conversion of the nitrogen compounds responding to the test to ammonium sulfate by mineralization of the sample with sulfuric acid, containing a high concentration of po
27、tassium sulfate in order to raise the boiling point of the mixture, in the presence of selenium which acts as a catalyst. 1) Liberation of ammonia from the ammonium sulfate by the addition of alkali and distillation into boric acid/indicator solution. Determination of ammonium ion in the distillate
28、by titration with standard acid. Alternatively, direct determination of ammonium ion in the mineralizate by spectrometry at 655 nm. (See clause 11.) 5 Reagents During the analysis, use only reagents of recognized analytical grade, and only distilled water prepared as described in 5.1. 5.1 Water, amm
29、onium-free, prepared by one of the following methods. 5.1.1 Ion exchange method Pass distilled water through a column of strongly acidic cation exchange resin (in the hydrogen form) and collect the eluate in a glass bottle provided with a well-fitting glass stopper. Add about 10 g of the same resin
30、to each litre of collected eluate for storage purposes. 5.1.2 Distillation method Add 0,10 0,01 ml of sulfuric acid (5.3) to1000 10ml of distilled water and redistil in all glass apparatus. Discard the first 50 ml of distillate, and then collect the distillate in a glass bottle provided with a well-
31、fitting glass stopper. Add about10 g of strongly acidic cation exchange resin (in the hydrogen form) to each litre of collected distillate. 5.2 Hydrochloric acid, = 1,18 g/ml. 5.3 Sulfuric acid, = 1,84 g/ml. WARNING This reagent causes severe burns. The highest purity sulfuric acid shall always be u
32、sed. Pay particular attention to the manufacturers specification with respect to its nitrogen content. 5.4 Sodium hydroxide, approximately 500 g/l solution. WARNING This reagent causes severe burns. 1) Selenium has been selected as the catalyst in preference to mercury because of concern in many cou
33、ntries about the toxicity of mercury. However, the toxicity of selenium must not be overlooked. See 11.2 for a suggested procedure for removal of selenium from mineralization residues.EN25663:1993 4 BSI 11-1999 Dissolve 500 20 g of sodium hydroxide in about800 ml of water. Cool to room temperature a
34、nd dilute to 1 litre with water in a measuring cylinder. 5.5 Hydrochloric acid, standard volumetric solution, c(HCl) . 0,10 mol/l. This solution shall be prepared by dilution of hydrochloric acid (5.2) followed by standardization by normal analytical procedures. Alternatively, a commercial solution
35、of guaranteed concentration may be used. 5.6 Hydrochloric acid, standard volumetric solution, c(HCl) . 0,02 mol/l. This solution shall be prepared by dilution of hydrochloric acid (5.2 or 5.5) followed by standardization by normal analytical procedures. Alternatively, a commercial solution of guaran
36、teed concentration may be used. 5.7 Boric acid/indicator, solution. 5.7.1 Dissolve 0,5 0,1 g of methyl red in about800ml of water and dilute to 1 litre with water in a measuring cylinder. 5.7.2 Dissolve 1,5 0,1 g of methylene blue in about800 ml of water and dilute to 1 litre with water in a measuri
37、ng cylinder. 5.7.3 Dissolve 20 1 g of boric acid (H 3 BO 3 ) in warm water. Cool to room temperature. Add 10 0,5 ml of methyl red solution (5.7.1) and 2,0 0,1 ml of methylene blue solution (5.7.2) and dilute to 1 litre with water in a measuring cylinder. 5.8 Catalyst mixture WARNING This mixture is
38、toxic. Inhalation of any dust resulting from its preparation or use shall be avoided. All residues containing selenium shall be collected for selenium recovery (11.2) or controlled disposal. Thoroughly mix 1 000 20 g of potassium sulfate and 10,0 0,2 g of selenium pellets. 5.9 Anti-bumping granules
39、6 Apparatus Ordinary laboratory apparatus and: 6.1 Kjeldahl mineralization flasks, specially designed, of sufficient capacity to accommodate the test portion volume to be used in the analysis, and in any event not exceeding 500 ml. They should preferably be suitable for direct attachment to the dist
40、illation apparatus (6.2). 6.2 Distillation apparatus, incorporating an anti-splash distillation head and a vertical condenser whose outlet can be submerged in the absorbent solution. If the Kjeldahl flasks (6.1) are not suitable for direct attachment to the distillation apparatus, separate distillat
41、ion flasks are necessary. NOTE ON PRELIMINARY CLEANING OF THE DISTILLATION APPARATUS Carry out the following procedure whenever the apparatus has been out of use for more than a few days. Add about 350 ml of water (5.1) to the distillation flask. Add a few anti-bumping granules (5.9), assemble the a
42、pparatus, and distil at least 100 ml. Discard the distillate and the residue in the distillation flask. 7 Sampling and samples Laboratory samples shall be collected in polyethylene or glass bottles. They should be analysed as quickly as possible, or else stored at between 2 and 5 C until analysed. A
43、cidification with sulfuric acid (5.3) to pH 2 may also be used as an aid to preservation, provided that possible contamination of the acidified sample by absorption of any atmospheric ammonia is avoided. 8 Procedure 8.1 Test portion If the approximate nitrogen concentration of the sample is known, t
44、he test portion volume can be selected from Table 1. Table 1 Selection of test portion 8.2 Blank test Proceed as described in 8.3, but using about 250 ml of water (5.1) instead of a test portion. Record the volume of hydrochloric acid (5.6) added. 8.3 Determination WARNING The mineralization procedu
45、re may evolve toxic sulfur dioxide gas. Hydrogen sulfide and/or hydrogen cyanide may also be liberated from polluted samples. The mineralization should therefore be carried out under an effective fume extraction system. Kjeldahl nitrogen concentration, N Volume of the test portion a mg/l ml up to10
46、250 10 to20 100 20 to50 50 50 to 100 25 a When using the 0,02 mol/l hydrochloric acid standard volumetric solution (5.6) for titration.EN25663:1993 BSI 11-1999 5 Place the test portion (8.1) in a Kjeldahl flask (6.1) and add, from a measuring cylinder, 10 ml of sulfuric acid (5.3) and 5,0 0,5 g of t
47、he catalyst mixture (5.8). Add a few anti-bumping granules(5.9) and boil the flask contents rapidly, under a suitable fume extraction system. The volume of the contents will decrease as water is boiled away, then evolution of white fumes will begin. After fume evolution has ended, periodically obser
48、ve the mineralizate and, after it has become clear and either colourless or light brown in colour, continue heating for a further 60 min. (See note 1.) After mineralization allow the flask to cool to room temperature. Meanwhile, measure 50 5 ml of indicator (5.7) into the receiving flask of the dist
49、illation apparatus. Ensure that the delivery tip of the condenser is below the surface of the indicator solution. Carefully add 250 50 ml of water (5.1) to the mineralization flask, together with a few anti-bumping granules (5.9). Then add, from a measuring cylinder, 50 ml of sodium hydroxide solution (5.4) and immediately attach the flask to the distillation apparatus. (See note 2.) Heat the distillation flask so that distillate collects at a rate of about 10 ml/min. Stop the di
