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!$W$:“1520123www.d
2、in.deDDIN EN 15476Fertilizers Determination of nitric and ammoniacal nitrogen according to DevardaEnglish version of DIN EN 15476:2009-04Dngemittel Bestimmung von Nitrat- und Ammoniumstickstoff nach DevardaEnglische Fassung DIN EN 15476:2009-04SupersedesDIN CEN/TS 15476:2006-12www.beuth.deDocument c
3、omprises 15 pagesDIN EN 15476:2009-04 2 National 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 Lebensmi
4、ttel und landwirtschaftliche Produkte (Food 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 diff
5、ers from DIN CEN/TS 15476:2006-12 as follows: a) In Tables 1 and 2, footnote a, 1stindent, 50 or 35 has been corrected to read 50. b) In Table 3, footnote a, 1stindent, 50 or 35 has been corrected to read 35. c) In Table 3, the approximate maximum quantity of nitrogen to be distilled has been change
6、d from 150 mg to 200 mg. d) Normative references have been updated. e) The standard has been editorially revised. Previous editions DIN CEN/TS 15476: 2006-12 National Annex NA (informative) Bibliography DIN ISO 5725-1, Accuracy (trueness and precision) of measurement methods and results Part 1: Gene
7、ral principles and definitions EUROPEAN STANDARDNORME EUROPENNEEUROPISCHE NORMEN 15476January 2009ICS 65.080 Supersedes CEN/TS 15476:2006 English VersionFertilizers - Determination of nitric and ammoniacal nitrogenaccording to DevardaEngrais - Dtermination de lazote nitrique et ammoniacalselon Devar
8、daDngemittel - Bestimmung von Nitrat- undAmmoniumstickstoff nach DevardaThis European Standard was approved by CEN on 30 November 2008.CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this EuropeanStandard the status of a national st
9、andard without any alteration. Up-to-date lists and bibliographical references concerning such nationalstandards may be obtained on application to 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
10、 language made by translationunder the responsibility of a CEN member into its own language and notified to the CEN Management Centre has the same status as theofficial versions.CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Fin
11、land,France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.EUROPEAN COMMITTEE FOR STANDARDIZATIONCOMIT EUROPEN DE NORMALISATIONEUROPISCHES KOMIT
12、EE FR NORMUNGManagement Centre: rue de Stassart, 36 B-1050 Brussels 2009 CEN All rights of exploitation in any form and by any means reservedworldwide for CEN national Members.Ref. No. EN 15476:2009: EEN 15476:2009 (E) 2 Contents Page Foreword 3 1 Scope 4 2 Normative references 4 3 Terms and definit
13、ions .4 4 Principle 4 5 Reagents .4 6 Apparatus .5 7 Sampling and sample preparation .7 8 Procedure .7 9 Calculation and expression of the result . 10 10 Precision 10 11 Test report . 10 Annex A (informative) Results of the inter-laboratory tests 12 Bibliography . 13 DIN EN 15476:2009-04 EN 15476:20
14、09 (E) 3 Foreword This document (EN 15476:2009) has been prepared by Technical Committee CEN/TC 260 “Fertilizers and liming materials”, 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 e
15、ndorsement, at the latest by July 2009, and conflicting national standards shall be withdrawn at the latest by July 2009. Attention is drawn to the 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 identif
16、ying any or all such patent rights. This document supersedes CEN/TS 15476:2006. This document has been prepared under a mandate given to CEN by the European Commission and the European Free Trade Association. According to the CEN/CENELEC Internal Regulations, the national standards organizations of
17、the following countries are bound to implement this European Standard: 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, Slova
18、kia, Slovenia, Spain, Sweden, Switzerland and the United Kingdom. DIN EN 15476:2009-04 EN 15476:2009 (E) 4 1 Scope This European Standard specifies a method for the determination of nitrate and ammoniacal nitrogen with reduction using Devarda alloy (modified for each of the variants a, b and c). The
19、 method is applicable to all nitrogenous fertilizers, including compound fertilizers, in which nitrogen is found exclusively in nitrate form or in ammoniacal and nitrate form. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated
20、references, only the edition cited applies. 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 materia
21、ls and soil improvers Vocabulary Part 1: General terms EN 12944-2:1999, Fertilizers and liming materials and soil inprovers 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 Fo
22、r the purposes of this document, the terms and definitions given in EN 12944-1:1999 and EN 12944-2:1999 apply. 4 Principle Reduction of nitrates and nitrites to ammonia in a strongly alkaline solution by means of a metallic alloy composed of 45 % Al, 5 % Zn and 50 % Cu (Devarda alloy). Distillation
23、of the ammonia and determination of the yield in a known volume of standard sulfuric acid; titration of the excess sulfuric acid by means of a standard solution of sodium or potassium hydroxide. 5 Reagents 5.1 General Use only reagents of recognized analytical grade and distilled or demineralized wa
24、ter, free from carbon dioxide and all nitrogenous compounds (grade 3 according to EN ISO 3696:1995). 5.2 Diluted hydrochloric acid, mix one volume of (HCl) = 1,18 g/ml with one volume of water. 5.3 Sulfuric acid (for variant a), c = 0,05 mol/l. 5.4 Sodium or potassium hydroxide solution (for variant
25、 a), carbonate free, c = 0,1 mol/l. 5.5 Sulfuric acid (for variant b, see NOTE 2 in 8.4), c = 0,1 mol/l. DIN EN 15476:2009-04 EN 15476:2009 (E) 5 5.6 Sodium or potassium hydroxide solution (for variant b, see NOTE 2 in 8.4), carbonate free, c = 0,2 mol/l. 5.7 Sulfuric acid (for variant c, see NOTE 2
26、 in 8.4), c = 0,25 mol/l. 5.8 Sodium or potassium hydroxide solution (for variant c, see NOTE 2 in 8.4), carbonate free, c = 0,5 mol/l. 5.9 Devarda alloy for analysis Powdered in such away that a mass fraction of 90 % to 100 % will pass through a sieve with apertures less than 0,25 mm square, a mass
27、 fraction of 50 % to 75 % will pass through a sieve with apertures of less than 0,075 mm square. Pre-packed bottles containing a maximum of 100 g are recommended. 5.10 Sodium hydroxide solution, 30 % of approximately (NaOH) = 1,33 g/ml, ammonia free. 5.11 Indicator solutions 5.11.1 Mixed indicator S
28、olution A: Dissolve 1 g of methyl red in 37 ml of sodium hydroxide solution c = 0,1 mol/l and make up to 1 l with water. Solution B: Dissolve 1 g of methylene blue in water and make up to 1 l. Mix one volume of A with two volumes of B. This indicator is violet in acid solution, grey in neutral solut
29、ion and green in alkaline solution. Use 0,5 ml (10 drops) of this indicator solution. 5.11.2 Methyl red indicator solution Dissolve 0,1 g of methyl red in 50 ml of 95 % ethanol. Make up to 100 ml with water and filter if necessary. This indicator may be used (4 to 5 drops) instead of the preceding o
30、ne. This indicator is red in acid solution and yellow in alkaline solution. 5.12 Ethanol, with a mass fraction of 95 % to 96 % ethanol. 5.13 Sodium nitrate, p. a. 6 Apparatus 6.1 Distillation apparatus Consisting of a round-bottomed flask of suitable capacity, connected to a condenser by a distillat
31、ion tube with a splash head, additionally equipped with a bubble trap on the receiving flask to prevent any loss of ammonia. The type of apparatus recommended for this determination is reproduced, showing all the features of construction, in Figure 1. The equipment is made of borosilicate glass. DIN
32、 EN 15476:2009-04 EN 15476:2009 (E) 6 An automatic distillation apparatus may be used as well provided that the results are statistically equivalent. Dimensions in millimetres Key 1 750 ml or 1 000 ml round-bottomed, long-necked flask with a bell mouth. 2 distillation tube with a splash head and a N
33、o 18 spherical joint at the issue 3 elbow tube with a No 18 spherical joint at the entrance, and a drip cone at the issue (a suitable rubber connection may be used instead of the spherical joint) 4 six-bulb condenser with an extension tube mounted on a rubber bung holding a bubble trap 5 750 ml rece
34、iving flask 6 bubble trap to prevent loss of ammonia Figure 1 Distillation apparatus DIN EN 15476:2009-04 EN 15476:2009 (E) 7 6.2 Pipettes, capacity of 10 ml, 20 ml, 25 ml, 50 ml, 100 ml and 200 ml. 6.3 Graduated flask, capacity 500 ml. 6.4 Rotary shaker, 35 to 40 revolutions per minute. 7 Sampling
35、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 preparation shall be carried out in accordance with EN 1482-2. 8 Procedure 8.1 Preparation of the solution According to Table 1, Table 2 or Table 3, depen
36、ding on the variant chosen weigh to the nearest 0,001 g, a quantity of 5 g, 7 g or 10 g of the prepared sample and transfer into a beaker glass of 250 ml. Add about 50 ml of water and 20 ml hydrochloric acid (5.2). Cover the beaker, heat until boiling and cool down. Filter the content of the beaker
37、and collect the filtrate and the rinse water in a volumetric flask of 500 ml, dilute to the mark with water and mix homogeneously. 8.2 Analysis of the solution The quantity of nitric nitrogen present in the aliquot part of the solution shall not exceed the maximum quantity expressed in Table 1, Tabl
38、e 2 or Table 3. According to the variant chosen, place in the receiving flask an exactly measured quantity of standard sulfuric acid as indicated in Table 1. Add the appropriate quantity of the chosen indicator solution (5.11.1 or 5.11.2) and finally, sufficient water to give a volume of 50 ml. The
39、end of the extension tube of the condenser shall be underneath the surface of the solution. Fill the bubble trap with water. Using a precision pipette, take an aliquot part as indicated in Table 1. Place it in the distillation flask. Add sufficient water to the distillation flask to obtain a volume
40、of 250 ml to 300 ml, 5 ml ethanol (5.12) and 4 g Devardas alloy (5.9), (see NOTE). Taking the necessary precautions to avoid loss of ammonia, add to the flask about 30 ml of 30 % sodium hydroxide solution (5.10) and finally, in the case of acid soluble samples an additional quantity sufficient to ne
41、utralize the quantity of hydrochloric acid (5.2) present in the aliquot part taken for the analysis. Connect the distillation flask to the apparatus, ensuring the tightness of connections. Carefully shake the flask to mix the contents. Warm gently, so that the release of hydrogen decreases appreciab
42、ly over about half an hour and the liquid will boil. Continue the distillation, increasing the heat so that at least 200 ml liquid distils in about 30 min (do not prolong the distillation beyond 45 min). When the distillation is complete, disconnect the receiving flask from the apparatus; carefully
43、wash the extension tube and bubble trap, collecting the rinsing in the titration flask and titrate the surplus acid with the standard solution of sodium or potassium hydroxide prescribed for the variant adopted (see NOTE 2 in 8.4). DIN EN 15476:2009-04 EN 15476:2009 (E) 8 NOTE In the presence of cal
44、cium salts such as calcium nitrate and calcium ammonium nitrate, it is necessary to add before distillation for each gram of sample present in the aliquot, 0,700 g sodium phosphate (Na2HPO4. 2H2O) to prevent the formation of Ca(OH)2. 8.3 Blank test Carry out a blank test (omitting the sample) under
45、the same conditions and refer to this in the calculation of the final result. 8.4 Control test Before carrying out the analysis, check that the apparatus is working properly and that the correct application of the method is used, using an aliquot of a freshly prepared solution of sodium nitrate (5.1
46、3) containing, according to the variant chosen, 0,050 g to 0,150 g of nitrate nitrogen. NOTE 1 When the sample solution is acid (addition of 20 ml of HCl (5.2) to dissolve the sample) the aliquot part taken for analysis is neutralized in the following way: to the distillation flask containing the ta
47、ken aliquot part add about 250 ml of water, the necessary quantity of one of the indicators (5.11.1, 5.11.2) and shake carefully. Neutralize with 2 mol/l sodium hydroxide solution (5.9) and acidify again with a drop of hydrochloric acid (5.2). Then proceed as indicated in 8.2 (second line). NOTE 2 S
48、tandard solutions of different strengths may be used for the back titration provided that the volumes used for the titration do not, as far as possible, exceed 40 ml to 45 ml. Table 1 Weighing, dilution and calculation variant a Declaration% N Amount to be weighed g Dilution ml Solution of sample to
49、 be distilled ml Expression of the resulta N = (50 A) F 0 to 5 5 to 10 10 to 15 15 to 20 20 to 40 10 10 7 5 7 500 500 500 500 500 50 25 25 25 10 (50 A) 0,14 (50 A) 0,28 (50 A) 0,40 (50 A) 0,56 (50 A) 1,00 Approximate maximum quantity of nitrogen to be distilled: 50 mg. Sulfuric acid c=0,05 mol/l to be placed in the receiving flask: 50 ml. Back titration with NaOH or KOH c=0,1 mol/l. aFor the purposes of the formula for expression of the result: 50 = millilitres of standard solution of sulfuric acid to be placed in the receiv
