00317396 PDF 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[.]
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 Confirmed July 2008 UDC 628.1/.3:620.1:546.17 BS EN 25663:1993 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 Belgium Denmark Finland France Germany Greece Iceland Ireland Italy Luxembourg Netherlands Norway Portugal Spain Sweden Switzerland United Kingdom This British Standard, having been prepared under the direction of the Environment and Pollution Standards Policy Committee, was published under the authority of the Standards Board and comes into effect on 15 November 1993 © BSI 11-1999 The following BSI references relate to the work on this standard: Committee reference EPC/44 Draft announced in BSI News August 1992 ISBN 580 21207 Oesterreichisches Normungsinstitut Institut belge de normalisation Dansk Standardiseringsraad Suomen Standardisoimisliito, r.y Association franỗaise de normalisation Deutsches Institut für Normung e.V Hellenic Organization for Standardization Technological Institute of Iceland National Standards Authority of Ireland Ente Nazionale Italiano di Unificazione Inspection du Travail et des Mines Nederlands Normalisatie-instituut Norges Standardiseringsforbund Instituto Portuguès da Qualidade Asociación Espola de Normalización y Certificación Standardiseringskommissionen i Sverige Association suisse de normalisation British Standards Institution Amendments issued since publication Amd No Date Comments BS EN 25663:1993 Contents Cooperating organizations National foreword Foreword Text of EN 25663 National annex NA (informative) Committees responsible National annex NB (informative) Cross-reference © BSI 11-1999 Page Inside front cover ii Inside back cover Inside back cover i BS EN 25663:1993 National foreword This British Standard has been prepared under the direction of the Environment 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 International 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 obligations Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, the EN title page, pages 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 ii © BSI 11-1999 EUROPEAN STANDARD EN 25663 NORME EUROPÉENNE September 1993 EUROPÄISCHE NORM 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, selenium English version Water quality — Determination of Kjeldahl nitrogen — Method after mineralization with selenium (ISO 5663:1984) Qualité de l’eau — Dosage de l’azote Kjeldahl —Méthode après minéralisation sélénium (ISO 5663:1984) Wasserbeschaffenheit — Bestimmung von Kjeldahl-Stickstoff — Verfahren nach Aufschluß mit 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 bibliographical 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 responsibility 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, Portugal, Spain, Sweden, Switzerland and United Kingdom CEN European Committee for Standardization Comité Européen de Normalisation Europäisches Komitee für Normung Central Secretariat: rue de Stassart 36, B-1050 Brussels © 1993 Copyright reserved to CEN members Ref No EN 25663:1993 E EN 25663:1993 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 (UAP) 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 March 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 United Kingdom Contents Foreword Scope and field of application Reference Definition Principle Reagents Apparatus Sampling and samples Procedure Expression of results 10 Interferences 11 Notes on procedure 12 Test report Table — Selection of test portion Table — Repeatability standard deviations Page 3 3 4 5 6 © BSI 11-1999 EN 25663:1993 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 nitrogen 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 waters 1.3 Range A Kjeldahl nitrogen content, ÕN, 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 ÕN = 000 mg/l 1.4 Limit of detection A practically determined (4 degrees of freedom) limit of detection, using a 100 ml test portion, is ÕN = mg/l 1.5 Sensitivity Using a 100 ml test portion, 1,0 ml of 0,02 mol/l hydrochloric acid is equivalent to ÕN = 2,8 mg/l Reference ISO 7150-1, Water quality — Determination of ammonium — Part 1: Manual spectrometric method Definition For the purpose of this International Standard, 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 Principle Mineralization 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 potassium 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 by titration with standard acid Alternatively, direct determination of ammonium ion in the mineralizate by spectrometry at 655 nm (See clause 11.) Reagents During the analysis, use only reagents of recognized analytical grade, and only distilled water prepared as described in 5.1 5.1 Water, ammonium-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 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) to 000 ± 10 ml 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-fitting glass stopper Add about 10 g of strongly acidic cation exchange resin (in the hydrogen form) to each litre of collected distillate 5.2 Hydrochloric acid, Õ = 1,18 g/ml 5.3 Sulfuric acid, Õ = 1,84 g/ml WARNING — This reagent causes severe burns The highest purity sulfuric acid shall always be used Pay particular attention to the manufacturer’s 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 countries 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 © BSI 11-1999 EN 25663:1993 Dissolve 500 ± 20 g of sodium hydroxide in about 800 ml of water Cool to room temperature and dilute to 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 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 guaranteed concentration may be used 5.7 Boric acid/indicator, solution 5.7.1 Dissolve 0,5 ± 0,1 g of methyl red in about 800 ml of water and dilute to litre with water in a measuring cylinder 5.7.2 Dissolve 1,5 ± 0,1 g of methylene blue in about 800 ml of water and dilute to litre with water in a measuring cylinder 5.7.3 Dissolve 20 ± g of boric acid (H3BO3) 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 litre with water in a measuring cylinder If the Kjeldahl flasks (6.1) are not suitable for direct attachment to the distillation apparatus, separate distillation 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 apparatus, and distil at least 100 ml Discard the distillate and the residue in the distillation flask 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 and °C until analysed Acidification with sulfuric acid (5.3) to < pH 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 Procedure 8.1 Test portion If the approximate nitrogen concentration of the sample is known, the test portion volume can be selected from Table Table — Selection of test portion 5.8 Catalyst mixture WARNING — This mixture is 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 000 ± 20 g of potassium sulfate and 10,0 ± 0,2 g of selenium pellets 5.9 Anti-bumping granules 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 distillation 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 Kjeldahl nitrogen concentration, ÕN Volume of the test portiona mg/l ml up to 10 250 10 to 20 100 20 to 50 50 50 to 100 25 a When using the 0,02 mol/l hydrochloric acid standard volumetric solution (5.6) for titration 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 procedure 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 © BSI 11-1999 EN 25663:1993 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 the 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 observe the mineralizate and, after it has become clear and either colourless or light brown in colour, continue heating for a further 60 (See note 1.) After mineralization allow the flask to cool to room temperature Meanwhile, measure 50 ± ml of indicator (5.7) into the receiving flask of the distillation 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 distillation when about 200 ml have been collected Titrate the distillate to a purple end-point with 0,02 mol/l hydrochloric acid (5.6) and record the volume added (See note 3) NOTE After water has boiled away, the rate of heating should be sufficient to reflux the acid mixture half-way up the neck of the flask This ensures the attainment of a sufficiently high mineralization temperature NOTE Where the flask is not compatible with the distillation apparatus, the contents must be transferred quantitatively to a suitable distillation flask This may conveniently be done at the water addition stage NOTE 0,10 mol/l hydrochloric acid (5.5) may be used for the titration of distillates from samples containing high concentrations of nitrogen V2 is the volume, in millilitres, of the standard volumetric hydrochloric acid used for the titration in the blank test (see 8.2); c is the exact concentration, expressed in moles per litre, of the hydrochloric acid used for titration; 14,01 is the relative atomic mass of nitrogen The result may be expressed as the mass concentration of nitrogen, ÕN, in milligrams per litre, or as the amount of substance concentration of nitrogen, cN, in micromoles per litre To convert ÕN to cN, multiply ÕN by 71,4 9.2 Repeatability Repeatability standard deviations have been determined as shown in Table 10 Interferences The presence of nitrate and/or nitrite may be a cause of both negative and positive errors Nitrate and/or nitrite may be reduced under the test conditions to ammonium, leading to falsely high results Nitrate and/or nitrite may also form ammonium salts with ammonium in the sample These salts may be decomposed at the temperature of the mineralization, resulting in the loss of nitrogen in gaseous forms and consequently low results If the concentration of nitrate and/or nitrite in the sample seems likely to cause unacceptable bias or loss of precision, separate reduction to ammonium should precede the mineralization process Falsely low results may also be obtained if the mineralization procedure is over-prolonged The procedure given in clause must be carefully observed Expression of results 9.1 Method of calculation The Kjeldahl nitrogen concentration, ÕN, expressed in milligrams per litre, is given by the formula V1 – V2 × c × 14,01 × 000 V0 where V0 is the volume, in millilitres, of the test portion (see 8.1); V1 is the volume, in millilitres, of the standard volumetric hydrochloric acid used for titration (see 8.3); © BSI 11-1999 EN 25663:1993 11 Notes on procedure 11.2 Suggested procedure for removal of selenium from mineralization residues 11.1 Ammonium ion may be determined directly in The residues should be collected into a glass bottle the mineralizate by spectrometry at 655 nm The labelled “Toxic” For removal of selenium, the bottle following procedure should be used contents must be made acid (pH 2) Reduction of this After allowing the flask to cool following acid solution with tin(II) chloride (added as a solid) mineralization, add 50 ± 10 ml of water (5.1) will produce a precipitate of red selenium which can to the flask Add drops of a solution then be filtered off and disposed of in a controlled of 4-nitrophenol, g/l Then, very slowly, add manner sodium hydroxide solution (5.4) while thoroughly mixing and cooling the solution until a pale yellow 12 Test report persistent colour develops Then add a few drops of The test report shall include the following sulfuric acid (5.3) until the yellow colour is information: discharged Transfer the solution quantitatively to a 200 ml volumetric flask and dilute to volume with a) a reference to this International Standard; water (5.1) Determine ammonium ion in this b) all information necessary for complete solution using the spectrometric procedure identification of the sample; (see ISO 7150-1) Calibration and blank solutions c) details of the storage and preservation of the must be prepared by following the above procedure laboratory sample before analysis; because the high concentration of sodium sulfate in the neutralized mineralizate solution will affect the d) a statement of the repeatability achieved; calibration of the spectrometric procedure The e) the results and the method of expression used; ammonium concentration, ÕN, expressed in f) details of any operations not included in this milligrams per litre, determined by the International Standard, or regarded as optional, spectrometric procedure must be multiplied by a together with any circumstance that may have factor 200/V0 where V0 is the test portion volume in affected the results millilitres (8.1), to obtain the Kjeldahl nitrogen concentration, ÕN, expressed in milligrams per litre, of the sample Table — Repeatability standard deviationsa Sample Urea solution Urea solution Urea solution Sewage Chemical waste Chemical waste Nitrogen concentration, ÕN mg/l 50 150 79c 16c 62c Test portion volume ml 500 100 100 50 200 100 Standard deviationb mg/l 0,027 0,31 2,69 0,68 0,19 0,48 Degrees of freedom 19 19 19 19 15 15 a Data b from France 0,1 mol/l hydrochloric acid was used for all titrations, except those for the ÕN = mg/l standard solution, for which 0,02 mol/l hydrochloric acid was used c Mean value from the determinations © BSI 11-1999 BS EN 25663:1993 National annex NA (informative) Committees responsible The United Kingdom participation in the preparation of this European Standard was entrusted by the Environment and Pollution Standards Policy Committee (EPC/-) to Technical Committee EPC/44, upon which the following bodies were represented: Association of Consulting Engineers British Association for Chemical Specialities British Gas plc Chemical Industries’ Association Industrial Water Society Institute of Petroleum Institution 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 Chemistry Scottish 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 Department of Trade and Industry (Laboratory of the Government Chemist) Department of the Environment for Northern Ireland Department of the Environment (Water Directorate) The following bodies were also represented in the drafting of the standard, through subcommittees and panels: British Agrochemicals Association Ltd British Ceramic Research Ltd British Laboratory Ware Association British Soft Drinks Association Ltd Department of Trade and Industry (Warren Spring Laboratory) GAMBICA (BEAMA Ltd.) Institute of Terrestrial Ecology Society of Chemical Industry South West Polytechnic Swimming Pool and Allied Trades Association Ltd National annex NB (informative) Cross-reference Publication referred to Corresponding British Standard ISO 7150-1:1984 BS 6068 Water quality Part Physical, chemical and biochemical methods Section 2.11:1984 Determination of ammonium: manual spectrometric method © BSI 11-1999 BS EN 25663:1993 ISO 5663:1984 BSI — British Standards Institution BSI is the independent national body responsible for preparing British Standards It presents the UK view on standards in Europe and at the international level It is incorporated by Royal Charter Revisions British Standards are updated by amendment or revision Users of British Standards should make sure that they possess the latest amendments or editions It is the constant aim of BSI to improve the quality of our products and services We would be grateful if anyone finding an inaccuracy or ambiguity while using this British Standard would inform the Secretary of the technical committee responsible, the identity of which can be found on the inside front cover Tel: 020 8996 9000 Fax: 020 8996 7400 BSI offers members an individual updating service called PLUS which ensures that subscribers automatically receive the latest editions of standards Buying standards Orders for all BSI, international and foreign standards publications should be addressed to Customer Services Tel: 020 8996 9001 Fax: 020 8996 7001 In response to orders for international standards, it is BSI policy to supply the BSI implementation of those that have been published as British Standards, unless otherwise requested Information on standards BSI provides a wide range of information on national, European and international standards through its Library and its Technical Help to Exporters Service Various BSI electronic information services are also available which give details on all its products and services Contact the Information Centre Tel: 020 8996 7111 Fax: 020 8996 7048 Subscribing members of BSI are kept up to date with standards developments and receive substantial discounts on the purchase price of standards For details of these and other benefits contact Membership Administration Tel: 020 8996 7002 Fax: 020 8996 7001 Copyright Copyright subsists in all BSI publications BSI also holds the copyright, in the UK, of the publications of the international standardization bodies Except as permitted under the Copyright, Designs and Patents Act 1988 no extract may be reproduced, stored in a retrieval system or transmitted in any form or by any means – electronic, photocopying, recording or otherwise – without prior written permission from BSI This does not preclude the free use, in the course of implementing the standard, of necessary details such as symbols, and size, type or grade designations If these details are to be used for any other purpose than implementation then the prior written permission of BSI must be obtained BSI 389 Chiswick High Road London W4 4AL If permission is granted, the terms may include royalty payments or a licensing agreement Details and advice can be obtained from the Copyright Manager Tel: 020 8996 7070