DIN EN 15750-2010 Fertilizers - Determination of total nitrogen in fertilizers containing nitrogen only as nitric ammoniacal and urea nitrogen by two different methods German versi.pdf

1、February 2010DEUTSCHE NORM English price group 11No 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!$Ca“1573262www

2、.din.deDDIN EN 15750Fertilizers Determination of total nitrogen in fertilizers containing nitrogen only asnitric, ammoniacal and urea nitrogen by two different methodsEnglish version of DIN EN 15750:2010-02Dngemittel Bestimmung von Gesamtstickstoff in Dngemitteln mit Stickstoff in Form von Ammonium,

3、Nitrat und Harnstoff unter Anwendung von zwei verschiedenen VerfahrenEnglische Fassung DIN EN 15750:2010-02SupersedesDIN CEN/TS 15750:2008-12www.beuth.deDocument comprises pages19DIN EN 15750:2010-02 National foreword This standard has been prepared by Technical Committee CEN/TC 260 “Fertilizers and

4、 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 and Agricultural Products Standards Committee), Working Committee NA 057-03-02 AA Dngemittel. Th

5、e European and International Standards referred to in this document have been published as the corresponding DIN EN or DIN EN ISO Standards with the same number, except for those below, which correspond as follows: EN ISO 3696 DIN ISO 3696 ISO 5725-1 DIN ISO 5725-1 Amendments This standard differs f

6、rom DIN CEN/TS 15750:2008-12 as follows: a) An introduction has been included explaining the status of the two test methods specified in this standard. b) In subclause 6.4 ”Calculation and expression of the results”, formulae (1), (2) and (3) have been changed into equations. c) In Tables 2 and 3 re

7、lating to precision data, “mg/kg” has been replaced with “%”. d) Normative references have been updated. e) The standard has been brought in line with the current rules of presentation. Previous editions DIN CEN/TS 15750: 2008-12 National Annex NA (informative) Bibliography DIN ISO 3696, Water for a

8、nalytical laboratory use Specification and test methods DIN ISO 5725-1, Accuracy (trueness and precision) of measurement methods and results Part 1: General principles and definitions 2 EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN 15750 October 2009 ICS 65.080 Supersedes CEN/TS 15750:2008Eng

9、lish Version Fertilizers - Determination of total nitrogen in fertilizers containing nitrogen only as nitric, ammoniacal and urea nitrogen by two different methods Engrais - Dtermination de la teneur en azote totale des engrais ne contenant lazote que sous forme nitrique, ammoniacale et urique selon

10、 deux mthodes diffrentesDngemittel - Bestimmung von Gesamtstickstoff in Dngemitteln mit Stickstoff in Form von Ammonium, Nitrat und Harnstoff unter Anwendung von zwei verschiedenen Verfahren This European Standard was approved by CEN on 20 September 2009. CEN members are bound to comply with the CEN

11、/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 CEN Management Centre or t

12、o 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 CEN Management Centre has the same status as the official versi

13、ons. 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, Slovakia, Slovenia, Sp

14、ain, Sweden, Switzerland and United Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUROPISCHES KOMITEE FR NORMUNG Management Centre: Avenue Marnix 17, B-1000 Brussels 2009 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national

15、Members. Ref. No. EN 15750:2009: EEN 15750:2009 (E) 2 Contents Page Foreword 3Introduction .41 Scope 52 Normative references 53 Terms and definitions .54 Principle 55 Sampling and sample preparation .66 Method A .67 Method B 128 Precision of methods A and B . 149 Test report . 15Annex A (informative

16、) Statistical results of the inter-laboratory tests . 16Bibliography . 17DIN EN 15750:2010-02 EN 15750:2009 (E) 3 Foreword This European Standard (EN 15750:2009) has been prepared by Technical Committee CEN/TC 260 “Fertilizers and liming materials”, the secretariat of which is held by DIN. This Euro

17、pean Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by April 2010, and conflicting national standards shall be withdrawn at the latest by April 2010. Attention is drawn to the possibility that some of the element

18、s 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 has been prepared under a mandate given to CEN by the European Commission and the European Free Trade Association. This document super

19、sedes CEN/TS 15750:2008. 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, Finland, France, Germany, Greece, Hungary,

20、Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and the United Kingdom. DIN EN 15750:2010-02 EN 15750:2009 (E) 4 Introduction This document specifies two different methods for the determinat

21、ion of the total nitrogen content in fertilizers. Based on the statistical results of the inter-laboratory tests, obtained with the same samples, the two methods produce equivalent results, and hence can be used both on decision of the user. DIN EN 15750:2010-02 EN 15750:2009 (E) 5 1 Scope This Euro

22、pean Standard specifies two different methods (Methods A and B) for the determination of the total nitrogen content in fertilizers. Method A specifies the titrimetric method after distillation according to ISO 5315:1984. Method B specifies a method by reduction of nitrate with iron and tin(II)-chlor

23、ide. 2 Normative references The following referenced documents 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, Fertilizer

24、s and liming materials Sampling and sample preparation Part 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 improvers Vocabulary Part 2: Terms relating to fertilizer

25、s EN ISO 385, Laboratory glassware Burettes (ISO 385:2005) EN ISO 3696, Water for analytical laboratory use Specification 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 Princi

26、ple 4.1 Method A Titrimetric method after distillation according to ISO 5315:1984 Reduction of nitrate to ammonia by chromium powder in acid medium. Conversion of organic and urea nitrogen into ammonium sulfate by digestion with concentrated sulfuric acid in the presence of a catalyst. Distillation

27、of the ammonia from an alkaline solution, absorption in an excess of standard volumetric sulfuric acid solution and back-titration with standard volumetric sodium hydroxide solution in the presence of methyl red or screened methyl red as indicator. 4.2 Method B Reduction of nitrate with iron and tin

28、(II)-chloride Reduction of nitrate to ammonia by iron powder and tin chloride in acid medium. Conversion of organic and urea nitrogen into ammonium sulfate by digestion with concentrated sulfuric acid in the presence of a catalyst. Distillation of the ammonia from an alkaline solution, absorption in

29、 an excess of standard volumetric sulfuric acid solution and back-titration with standard volumetric sodium hydroxide solution in the presence of an indicator solution. DIN EN 15750:2010-02 EN 15750:2009 (E) 6 5 Sampling and sample preparation Sampling is not part of the methods specified in this Eu

30、ropean Standard. A recommended sampling method is given in EN 1482-1. Sample preparation shall be carried out in accordance with EN 1482-2. 6 Method A 6.1 Reagents Use only reagents of recognized analytical grade having, in particular, low nitrogen contents and distilled or demineralized water (grad

31、e 3 according to EN ISO 3696). 6.1.1 Chromium metal, powder of particle size less than or equal to 250 m. 6.1.2 Aluminium oxide, fused, pumice is suitable. 6.1.3 Anti-foaming agent, for example paraffin wax of melting point not lower than 100 C, or a silicone. 6.1.4 Ammonium nitrate, dried at 100 C

32、to constant mass. 6.1.5 Digestion catalyst mixture, finely ground, comprising potassium sulfate (K2SO4): 1 000 g; copper(II) sulfate pentahydrate (CuSO4.5H2O): 50 g. 6.1.6 Sulfuric acid, concentrated, approximately 1,84 g/ml. 6.1.7 Hydrochloric acid, concentrated, approximately 1,18 g/ml. 6.1.8 Sodi

33、um hydroxide, approximately 400 g/l solution. 6.1.9 Sodium hydroxide, standard volumetric solution, c(NaOH) = 0,10 mol/l. 6.1.10 Sulfuric acid, standard volumetric solution, c(H2SO4) = 0,25 mol/l. 6.1.11 Sulfuric acid, standard volumetric solution, c(H2SO4) = 0,10 mol/l. 6.1.12 Sulfuric acid, standa

34、rd volumetric solution, c(H2SO4) = 0,05 mol/l. 6.1.13 Indicator solution, use either the screened methyl red solution (6.1.13.1) or the methyl red solution (6.1.13.2). 6.1.13.1 Screened methyl red, ethanolic indicator solution; mix 50 ml of a 2 g/l ethanolic solution of methyl red with 50 ml of a 1

35、g/l ethanolic solution of methylene blue. DIN EN 15750:2010-02 EN 15750:2009 (E) 7 6.1.13.2 Methyl red, ethanolic indicator solution; dissolve 0,1 g of methyl red in 50 ml of 95 % (volume fraction) ethanol. 6.1.14 pH indicator paper, wide range. 6.2 Apparatus Common laboratory equipment and glasswar

36、e, in particular equipment according to 6.2.1 to 6.2.5. 6.2.1 Digestion apparatus, comprising an 800 ml Kjeldahl flask and a pear-shaped hollow glass stopper. 6.2.2 Distillation apparatus The components of the distillation apparatus may be connected by means of rubber bungs and tubing or by the use

37、of spherical ground glass joints. Spherical ground glass joints should be held spring clamps to ensure that they are leak tight. Rubber bungs and tubing shall be replaced when they begin to perish or show signs of wear. Suitable apparatus is illustrated in Figure 1. An automatic distillation apparat

38、us may also be used, provided that the results are statistically equivalent. DIN EN 15750:2010-02 EN 15750:2009 (E) 8 Dimensions in millimetres Key 1 Kjeldahl flask (6.2.1) or round-bottomed, long-necked flask of 1 000 ml capacity 2 distillation tube with a single-bulb splash head, connected to the

39、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 connection) 3 funnel with a polytetrafluoroethylene (PTFE) tap (6) (the tap may likewise be replaced by a rubber connection with a clip) 4 seven-bulb cond

40、enser 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 tube is effected by means of a rubber tube, the spherical joint may be replaced by a suitable rubber bung) 5 500 ml flas

41、k in which the distillate is collected 6 PTFE-tap a hole Figure 1 Typical distillation apparatus (using a round bottom flask) DIN EN 15750:2010-02 EN 15750:2009 (E) 9 6.2.3 Anti-bumping granules, or anti-bumping device, consisting of a 100 mm 5 mm glass rod connected to a 25 mm length of polyethylen

42、e tubing. 6.2.4 Two burettes, of capacity 50 ml, according to EN ISO 385, I class A. 6.2.5 Glass beads, of diameter 2 mm to 3 mm. 6.3 Procedure 6.3.1 Test portion Weight, to the nearest 0,001 g, between 0,5 g and 2,0 g of the test sample, containing not more than 60 mg of nitrate nitrogen and 235 mg

43、 of total nitrogen. 6.3.2 Determination 6.3.2.1 Reduction NOTE 1 This step is not required if nitrate nitrogen is known to be absent. Transfer the test portion (6.3.1) to the flask (6.2.1) and add sufficient water to make up the total volume to 35 ml. Allow the flask to stand for 10 min with occasio

44、nal gentle swirling to ensure dissolution of all nitrate salts. Add 1,2 g of the chromium powder (6.1.1) and 7 ml of the hydrochloric acid solution (6.1.7). Allow the flask to stand for at least 5 min, but not more than 10 min, at ambient temperature. Place the flask on a heating device in a fume cu

45、pboard with the heat input regulated to pass a 7 min to 7,5 min boil test and heat the flask for 4,5 min. Remove from the heat and allow to cool. NOTE 2 The heat input is that required to bring 250 ml of water at 25 C to a “rolling“ boil in 7 min to 7,5 min. 6.3.2.2 Hydrolysis NOTE This step can be

46、used instead of the digestion (6.3.2.3) if it is known that the only forms of organic nitrogen present are urea and cyanamide forms. Stand the flask in a fume cupboard and add 1,5 g of the fused aluminium oxide (6.1.2). Carefully add 25 ml of the sulfuric acid (6.1.6) to the flask. Insert the pear-s

47、haped hollow glass stopper into the neck of the flask and place on a heating device and initially heat until gently boiling. Then adjust the heat input to pass a 7 min to 7,5 min boil test (see 6.3.2.1, NOTE 2). Continue to heat the flask and contents until dense white fumes of sulfuric acid have be

48、en involving for at least 15 min. Allow the flask to cool to room temperature and carefully add 250 ml of water. Allow the flask to cool. 6.3.2.3 Digestion NOTE This step is necessary only if organic forms of nitrogen other than urea or cyanamide forms are present (see 6.3.2.2) or in the case of fer

49、tilizers of unknown composition. Place the flask in a fume cupboard and add 22 g of the digestion catalyst mixture (6.1.5) and 1,5 g of the fused aluminium oxide (6.1.2). Carefully add 30 ml of the sulfuric acid (6.1.6) to the flask and add 0,5 g of the DIN EN 15750:2010-02 EN 15750:2009 (E) 10 anti-foaming agent (6.1.3) to reduce foaming. Insert the pear-shaped hollow glass stopper into the neck of the flask and place on a heating device with the heat input adjusted to pass a 7 min to