1、April 2009DEUTSCHE NORM English price group 10No part of this standard may be reproduced without prior permission ofDIN Deutsches Institut fr Normung e. V., Berlin. Beuth Verlag GmbH, 10772 Berlin, Germany,has the exclusive right of sale for German Standards (DIN-Normen).ICS 65.080!$W$;“1520124www.d
2、in.deDDIN EN 15478Fertilizers Determination of total nitrogen in ureaEnglish version of DIN EN 15478:2009-04Dngemittel Bestimmung von Gesamtstickstoff in HarnstoffEnglische Fassung DIN EN 15478:2009-04SupersedesDIN CEN/TS 15478:2006-12www.beuth.deDocument comprises 16 pagesDIN EN 15478:2009-04 2 Nat
3、ional foreword This standard has been prepared by Technical Committee CEN/TC 260 “Fertilizers and liming materials” (Secretariat: DIN, Germany) under the mandate M/335. The responsible German body involved in its preparation was the Normenausschuss Lebensmittel und landwirtschaftliche Produkte (Food
4、 and Agricultural Products Standards Committee), Technical Committee NA 057-03-02 AA Dngemittel. The DIN Standard corresponding to the International Standard referred to in this document is as follows: ISO 5725-1 DIN ISO 5725-1 Amendments This standard differs from DIN CEN/TS 15478:2006-12 as follow
5、s: a) In subclause 5.2, potassium sulfate has been replaced by Kjeldahl tablets. b) In the key of equation (1), line 1, 0,5 ml has been replaced by 0,5 mol/l. c) In the key of equation (1), line 2, 0,05 ml has been replaced by 0,05 mol/l. d) Normative references have been updated. e) The standard ha
6、s been editorially revised. Previous editions DIN CEN/TS 15478: 2006-12 National Annex NA (informative) Bibliography DIN ISO 5725-1, Accuracy (trueness and precision) of measurement methods and results Part 1: General principles and definitions EUROPEAN STANDARDNORME EUROPENNEEUROPISCHE NORMEN 15478
7、January 2009ICS 65.080 Supersedes CEN/TS 15478:2006 English VersionFertilizers - Determination of total nitrogen in ureaEngrais - Dtermination de lazote total dans lure Dngemittel - Bestimmung von Gesamtstickstoff inHarnstoffThis European Standard was approved by CEN on 30 November 2008.CEN members
8、are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this EuropeanStandard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such nationalstandards may be obtained on application to
9、the CEN Management Centre or to any CEN member.This European Standard exists in three official versions (English, French, German). A version in any other language made by translationunder the responsibility of a CEN member into its own language and notified to the CEN Management Centre has the same
10、status as theofficial versions.CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland,France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,Romania
11、, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.EUROPEAN COMMITTEE FOR STANDARDIZATIONCOMIT EUROPEN DE NORMALISATIONEUROPISCHES KOMITEE FR NORMUNGManagement Centre: rue de Stassart, 36 B-1050 Brussels 2009 CEN All rights of exploitation in any form and by any means reservedworldw
12、ide for CEN national Members.Ref. No. EN 15478:2009: EEN 15478:2009 (E) 2 Contents Page Foreword 3 1 Scope 4 2 Normative references 4 3 Terms and definitions .4 4 Principle 4 5 Reagents .4 6 Apparatus .5 7 Sampling and sample preparation 10 8 Procedure 10 9 Calculation and expression of the result .
13、 11 10 Precision 11 11 Test report . 12 Annex A (informative) Results of the inter-laboratory tests 13 Bibliography . 14 DIN EN 15478:2009-04 EN 15478:2009 (E) 3 Foreword This document (EN 15478:2009) has been prepared by Technical Committee CEN/TC 260 “Fertilizers and liming materials”, the secreta
14、riat 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 July 2009, and conflicting national standards shall be withdrawn at the latest by July 2009. Attention is drawn to the
15、 possibility that some of the elements of this document may be the subject of patent rights. CEN and/or CENELEC shall not be held responsible for identifying any or all such patent rights. This document supersedes CEN/TS 15478:2006. This document has been prepared under a mandate given to CEN by the
16、 European Commission and the European Free Trade Association. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finlan
17、d, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and the United Kingdom. DIN EN 15478:2009-04 EN 15478:2009 (E) 4 1 Scope This European Standard specifies
18、 a method for the determination of total nitrogen in urea. This method is applied exclusively to urea fertilizers which are nitrate free. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited app
19、lies. For undated references, the latest edition of the referenced document (including any amendments) applies. EN 1482-2, Fertilizers and liming materials Sampling and sample preparation Part 2: Sample preparation EN 12944-1:1999, Fertilizers and liming materials and soil improvers Vocabulary Part
20、1: General terms EN 12944-2:1999, Fertilizers and liming materials and soil improvers Vocabulary Part 2: Terms relating to fertilizers EN ISO 3696:1995, Water for analytical laboratory use Specification and test methods (ISO 3696:1987) 3 Terms and definitions For the purposes of this document, the t
21、erms and definitions given in EN 12944-1:1999 and EN 12944-2:1999 apply. 4 Principle Urea is transformed quantitatively into ammonia by boiling in the presence of sulfuric acid. The ammonia thus obtained is distilled from an alkaline medium, the distillate being collected in an excess of standard su
22、lfuric acid. The excess acid is titrated by means of a standard alkaline solution. 5 Reagents 5.1 General Use only reagents of recognized analytical grade and distilled or demineralized water, free from carbon dioxide and all nitrogenous compounds (grade 3 according to EN ISO 3696:1995). 5.2 Kjeldah
23、l tablets, 5 g/tablet containing 100 parts K2SO4to 1 part selenium. DIN EN 15478:2009-04 EN 15478:2009 (E) 5 5.3 Sulfuric acid, concentrated (20= 1,84 g/ml). 5.4 Sodium hydroxide solution, approximately NaOH 500 g/l. 5.5 Sulfuric acid, c = 0,05 mol/l, to use for the blank test. 5.6 Sodium or potassi
24、um hydroxide solution, carbonate free, c = 0,1 mol/l, to use for the blank test. 5.7 Sulfuric acid, c = 0,5 mol/l. 5.8 Sodium or potassium hydroxide solution, carbonate free, c = 1,0 mol/l. 5.9 Indicator solutions 5.9.1 Mixed indicator Solution A: Dissolve 1 g of methyl red in 37 ml of 0,1 mol/l sod
25、ium hydroxide solution and make up to one litre with water. Solution B: Dissolve 1 g of methylene blue in water and make up to one litre. Mix one volume of A with two volumes of B. This indicator is violet in an acid solution, grey in a neutral solution and green in an alkaline solution; use 0,5 ml
26、(10 drops). 5.9.2 Methyl red indicator solution Dissolve 0,1 g of methyl red in 50 ml of 95 % ethanol and make up to 100 ml with water. Filter if necessary. This indicator (4 or 5 drops) may be used instead of the preceding one. This indicator is red in acid solution and yellow in alkaline solution.
27、 5.10 Anti-bump granules, for example pumice stone, washed in hydrochloric acid and calcined. 5.11 Urea, p. a. 6 Apparatus 6.1 Distillation apparatus Consisting of a round-bottomed flask of suitable capacity connected to a condenser by means of a splash head. The equipment is made of borosilicate gl
28、ass. NOTE The different types of equipment recommended for this determination are reproduced showing all the features of construction in Figures 1, 2, 3, and 4. Automatic distillation apparatus may be used as well provided that the results are statistically equivalent. DIN EN 15478:2009-04 EN 15478:
29、2009 (E) 6 Dimensions in millimetres Key 1 round-bottomed, long-necked flask of 1 000 ml capacity 2 distillation tube with a splash head, connected to the condenser by means of a spherical joint (No 18) (the spherical joint for the connection to the condenser may be replaced by an appropriate rubber
30、 connection) 3 funnel with a polytetrafluoroethylene (PTFE) tap (6) for the addition of sodium hydroxide 4 six-bulb condenser with spherical joint (No 18) at the entrance, and joined at the issue to a glass extension tube by means of a small rubber connection (when the connection to the distillation
31、 tube is effected by means of a rubber tube, the spherical joint may be replaced by a suitable rubber bung) 5 500 ml flask in which the distillate is collected 6 PTFE-tap (the tap may likewise be replaced by a rubber connection with a clip) Figure 1 Distillation apparatus 1 DIN EN 15478:2009-04 EN 1
32、5478:2009 (E) 7 Dimensions in millimetres Key 1 round-bottomed, short-necked flask of 1 000 ml capacity with a spherical joint (No 35) 2 distillation tube with a splash head, equipped with a spherical joint (No 35) at the entrance and a spherical joint (No 18) at the issue, connected at the side to
33、a funnel with a polytetrafluoroethylene (PTFE) tap (6) for the addition of sodium hydroxide 3 six-bulb condenser with a spherical joint (No 18) at the entrance and joined at the issue to a glass extension tube by means of a small rubber connection 4 500 ml flask in which the distillate is collected
34、5 PTFE-tap a enlarged description Figure 2 Distillation apparatus 2 DIN EN 15478:2009-04 EN 15478:2009 (E) 8 Dimensions in millimetres Key 1 round-bottomed, long-necked flask of 750 ml or 1 000 ml capacity with, a bell mouth 2 distillation tube with a splash head and a spherical joint (No 18) at the
35、 issue 3 elbow tube with a spherical joint (No 18) at the entrance, and a drip cone (the connection to the distillation tube may be effected by means of a rubber tube instead of a spherical joint) 4 six-bulb condenser joined at the issue to a glass extension tube by means of a small rubber connectio
36、n 5 500 ml flask in which the distillate is collected Figure 3 Distillation apparatus 3 DIN EN 15478:2009-04 EN 15478:2009 (E) 9 Dimensions in millimetres Key 1 round-bottomed, long-necked flask of 1 000 ml capacity with a bell mouth 2 distillation tube with a splash head and a spherical joint (No 1
37、8), at the issue, connected at the side to a funnel with a polytetrafluoroethylene (PTFE) tap (5) for the addition of sodium hydroxide (a suitable rubber bung may be used instead of the spherical joint 3 six-bulb condenser with a spherical joint (No 18) at the entrance, joined at the issue, by a rub
38、ber connection, to a glass extension tube (when the connection to the distillation tube is effected by means of a rubber tube, the spherical joint may be replaced by a suitable rubber bung) 4 500 ml flask for the collection of the distillate 5 PTFE-tap (the tap may be replaced by a rubber connection
39、 with an appropriate clip) Figure 4 Distillation apparatus 4 DIN EN 15478:2009-04 EN 15478:2009 (E) 10 6.2 Graduated flask, capacity 500 ml. 7 Sampling and sample preparation Sampling is not part of the method specified in this document. A recommended sampling method is given in EN 1482-1. Sample pr
40、eparation shall be carried out in accordance with EN 1482-2. 8 Procedure 8.1 Preparation of the solution Weigh to the nearest 0,001 g about 500 mg of the prepared sample and transfer with 10 ml demineralised water to a 800 ml Kjeldahl flask. Add, while gently swirling 30 ml sulfuric acid (5.3) and 1
41、 Kjeldahl tablet (5.2). 8.2 Analysis of the solution 8.2.1 Digestion step Put the Kjeldahl flask in a fume cupboard. Place on a heating device and heat until boiling, with an input that is required to bring 250 ml of water at 25 C to a “rolling boil“ in 20 min to 30 min. Continue to heat the flask a
42、nd contents for approximately 1 h, until dense white fumes of sulfuric acid are escaping for at least 15 min. Allow the flask to cool to 25 C. 8.2.2 Distillation step Measure into a 500 ml Erlenmeyer receiving flask 30,00 ml of the 0,5 mol/l sulfuric acid solution (5.7). Add 270 ml water and add fou
43、r or five drops of the indicator solution (5.9.) and place the Erlenmeyer flask in such a way that the end of the delivery tube is at least 3 cm below the surface of the liquid. Add 250 ml water to the Kjeldahl flask and several grains of pumice stone (5.10) in order to control the boiling. Assemble
44、 the distillation apparatus and taking care to avoid any loss of ammonia, add to the contents of the Kjeldahl flask carefully 120 ml of the sodium hydroxide solution (5.4). Agitate the flask to thoroughly mix the contents. Apply heat increasing the rate of heating progressively until finally the con
45、tents of the flask are boiling briskly. Most of the ammonia is expelled within 15 min. Continue the distillation until 150 ml of distillate has been collected. Then lower the Erlenmeyer flask receiver so that the end of the delivery tube is out of the liquid and continue the distillation for a few m
46、ore minutes. Rinse the outside of the delivery tube with a small amount of water into the Erlenmeyer flask. Back titrate the excess of acid with the 1,0 mol/l sodium hydroxide solution (5.8) to the neutral colour of the indicator (5.9). 8.3 Blank At the same time as the determination carry out a bla
47、nk test, using the same apparatus and the same quantities of all the reagents and water, but omitting the test portion and using 20,00 ml of the 0,05 mol/l sulfuric acid solution (5.5) and back titrating with the 0,1 mol/l sodium hydroxide solution (5.6). 8.4 Control test Before carrying out the ana
48、lysis, check that the apparatus is working properly and that the correct application of the method is used, using an aliquot part of a freshly prepared solution of urea (5.11). DIN EN 15478:2009-04 EN 15478:2009 (E) 11 9 Calculation and expression of the result Express the result of the analysis as
49、a percentage of nitrogen (N) contained in the fertilizer as received for analysis. Calculate the mass fraction of total nitrogen, wNin percent, using the following equation: mtVttVtw10014)220()230(423211N= (1) where 30 is the volume, in millilitres of the 0,5 mol/l sulfuric acid solution (5.7); 20 is the volume, in millilitres of the 0,05 mol/l sulfuric acid solution (5.5); V1is the volume, in millilitres of the 1,0 mol/l sodium hydroxide solution (5.8) used for the determination; V2is the volume, in millilitres of the 0,1 mol/l so
