BS EN 15476-2009 Fertilizers - Determination of nitric and ammoniacal nitrogen according to Devarda《肥料 根据德瓦达法测定氮和氨态氮含量》.pdf

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1、BS EN 15476:2009ICS 65.080NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBRITISH STANDARDFertilizers Determination ofnitric and ammoniacalnitrogen according toDevardaThis British Standardwas published under theauthority of the StandardsPolicy and StrategyCommittee on 28 Februa

2、ry2009 BSI 2009ISBN 978 0 580 62382 0Amendments/corrigenda issued since publicationDate CommentsBS EN 15476:2009National forewordThis British Standard is the UK implementation of EN 15476:2009. Itsupersedes DD CEN/TS 15476:2006 which is withdrawn.The UK participation in its preparation was entrusted

3、 to TechnicalCommittee CII/37, Fertilisers and related chemicals.A list of organizations represented on this committee can be obtained onrequest to its secretary.This publication does not purport to include all the necessary provisionsof a contract. Users are responsible for its correct application.

4、Compliance with a British Standard cannot confer immunityfrom legal obligations.BS EN 15476:2009EUROPEAN STANDARDNORME EUROPENNEEUROPISCHE NORMEN 15476January 2009ICS 65.080 Supersedes CEN/TS 15476:2006 English VersionFertilizers - Determination of nitric and ammoniacal nitrogenaccording to DevardaE

5、ngrais - Dtermination de lazote nitrique et ammoniacalselon DevardaDngemittel - 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 condit

6、ions 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 the CEN Management Centre or to any CEN member.This European Standard exists in three of

7、ficial 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 status as theofficial versions.CEN members are the national standards bodies of Austria,

8、 Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland,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 F

9、OR 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 reservedworldwide for CEN national Members.Ref. No. EN 15476:2009: EBS EN 15476:2009EN 15476:2009 (E)

10、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 .7 8 Procedure .7 9 Calculation and expression of the result . 10 10 Precision 10 11 Test report . 10 Annex A (informative) Results of

11、 the inter-laboratory tests 12 Bibliography . 13 BS EN 15476:2009EN 15476:2009 (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 statu

12、s 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 possibility that some of the elements of this document may be the subject of

13、 patent rights. CEN and/or CENELEC shall not be held responsible for identifying 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 th

14、e 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, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuan

15、ia, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and the United Kingdom. BS EN 15476:2009EN 15476:2009 (E) 4 1 Scope This European Standard specifies a method for the determination of nitrate and ammoniacal nitrogen with reduction

16、using Devarda alloy (modified for each of the variants a, b and c). The 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 docum

17、ents are indispensable for the application of this document. For dated 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 Par

18、t 2: Sample preparation EN 12944-1:1999, Fertilizers and liming materials 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 Sp

19、ecification and test methods (ISO 3696:1987) 3 Terms and definitions For 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

20、 composed of 45 % Al, 5 % Zn and 50 % Cu (Devarda alloy). Distillation 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 re

21、agents 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 Diluted hydrochloric acid, mix one volume of (HCl) = 1,18 g/ml with one volume of water. 5.3 Sulfuric acid (for variant a),

22、c = 0,05 mol/l. 5.4 Sodium or potassium hydroxide solution (for variant 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. BS EN 15476:2009EN 15476:2009 (E) 5 5.6 Sodium or potassium hydroxide solution (for variant b, see NOTE 2 in 8.4), carbonate

23、 free, c = 0,2 mol/l. 5.7 Sulfuric acid (for variant c, see NOTE 2 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 pa

24、ss through a sieve with apertures less than 0,25 mm square, a mass 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/m

25、l, ammonia free. 5.11 Indicator solutions 5.11.1 Mixed indicator Solution 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

26、. This indicator is violet in acid solution, grey in neutral solution 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. Th

27、is indicator may be used (4 to 5 drops) instead of the preceding one. 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 f

28、lask of suitable capacity, connected to a condenser by a distillation 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 construct

29、ion, in Figure 1. The equipment is made of borosilicate glass. BS EN 15476:2009EN 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

30、 a bell mouth. 2 distillation tube with a splash head and a No 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

31、 mounted on a rubber bung holding a bubble trap 5 750 ml receiving flask 6 bubble trap to prevent loss of ammonia Figure 1 Distillation apparatus BS EN 15476:2009EN 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 Rot

32、ary shaker, 35 to 40 revolutions per minute. 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 preparation shall be carried out in accordance with EN 1482-2. 8 Procedure 8.1 Preparation of the

33、solution According to Table 1, Table 2 or Table 3, depending 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

34、boiling and cool down. Filter the content of the beaker 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 no

35、t exceed the maximum quantity expressed in Table 1, Table 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 f

36、inally, sufficient water to give a volume of 50 ml. The 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 suffic

37、ient water to the distillation flask to obtain a volume 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

38、 soluble samples an additional quantity sufficient to neutralize 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 gen

39、tly, so that the release of hydrogen decreases appreciably 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, disco

40、nnect the receiving flask from the apparatus; carefully 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). BS EN 15476:

41、2009EN 15476:2009 (E) 8 NOTE In the presence of calcium 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

42、Carry out a blank test (omitting the sample) under 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

43、 a freshly prepared solution of sodium nitrate (5.13) 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 followi

44、ng way: to the distillation flask containing the taken 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

45、proceed as indicated in 8.2 (second line). NOTE 2 Standard 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 Amoun

46、t to be weighed g Dilution ml Solution of sample to 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

47、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 receiving flask; A = mill

48、ilitres of sodium or potassium hydroxide used for the back titration; F = factor comprising the amount weighed, the dilution, the aliquot part of solution of the sample to be distilled and the volumetric equivalent; N = percentage mass fraction of nitrogen. BS EN 15476:2009EN 15476:2009 (E) 9 Table

49、2 Weighing, dilution and calculation variant b Declaration % N Amount to be weighed g Dilution ml Solution of sample to 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 7 500 500 500 500 500 100 50 50 50 20 (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: 100 mg. Sulfuric acid c=0,1 mol/l to be placed in the receiving flask: 50 ml. Back titration with NaOH or KOH c=0,2 mol/l. a