EN 15750-2009 en Fertilizers - Determination of total nitrogen in fertilizers containing nitrogen only as nitric ammoniacal and urea nitrogen by two different methods《肥料 用两种不同的方法对含.pdf

1、BS EN 15750:2009ICS 65.080NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBRITISH STANDARDFertilizers Determination oftotal nitrogen infertilizers containingnitrogen only as nitric,ammoniacal andurea nitrogen by twodifferent methodsThis British Standardwas published under theau

2、thority of the StandardsPolicy and StrategyCommittee on 28 February2010 BSI 2010ISBN 978 0 580 66426 7Amendments/corrigenda issued since publicationDate CommentsBS EN 15750:2009National forewordThis British Standard is the UK implementation of EN 15750:2009. Itsupersedes DD CEN/TS 15750:2008 which i

3、s withdrawn.The UK participation in its preparation was entrusted to TechnicalCommittee CII/37, Fertilisers and related chemicals.A list of organizations represented on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 provisions

4、of a contract. Users are responsible for its correct application.Compliance with a British Standard cannot confer immunityfrom legal obligations.BS EN 15750:2009EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN 15750 October 2009 ICS 65.080 Supersedes CEN/TS 15750:2008English Version Fertilizers

5、- 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 deux mthodes diffrentesD

6、ngemittel - 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/CENELEC Internal Regulat

7、ions 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 to any CEN member. This Eu

8、ropean 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 versions. CEN members are the

9、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, Spain, Sweden, Switzerland

10、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 Members. Ref. No. EN 1575

11、0:2009: EBS EN 15750:2009EN 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) Statist

12、ical results of the inter-laboratory tests . 16Bibliography . 17BS EN 15750:2009EN 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 European Standard

13、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 elements of this docu

14、ment 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 supersedes CEN/TS 1

15、5750:2008. 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, Iceland, Irela

16、nd, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and the United Kingdom. BS EN 15750:2009EN 15750:2009 (E) 4 Introduction This document specifies two different methods for the determination of the total ni

17、trogen 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. BS EN 15750:2009EN 15750:2009 (E) 5 1 Scope This European Standard specifies

18、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)-chloride. 2 Normative referen

19、ces 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, Fertilizers and liming materials S

20、ampling 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 fertilizers EN ISO 385, Laboratory

21、 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 Principle 4.1 Method A Titrime

22、tric 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 of the ammonia from an a

23、lkaline 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(II)-chloride Reduction

24、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 an excess of standard v

25、olumetric sulfuric acid solution and back-titration with standard volumetric sodium hydroxide solution in the presence of an indicator solution. BS EN 15750:2009EN 15750:2009 (E) 6 5 Sampling and sample preparation Sampling is not part of the methods specified in this European Standard. A recommende

26、d 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 (grade 3 according to EN ISO 3696)

27、. 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 to constant mass. 6.1.5 Diges

28、tion 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 Sodium hydroxide, approximately 4

29、00 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, standard volumetric solution, c(H2S

30、O4) = 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 g/l ethanolic solution of met

31、hylene blue. BS EN 15750:2009EN 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 glassware, in particular equipment accordi

32、ng 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 of spherical ground glass joints.

33、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 apparatus may also be used, provided that

34、 the results are statistically equivalent. BS EN 15750:2009EN 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 condenser by means of a spherical joint

35、 (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 condenser with spherical joint (No 18) at t

36、he 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 flask in which the distillate is collected

37、6 PTFE-tap a hole Figure 1 Typical distillation apparatus (using a round bottom flask) BS EN 15750:2009EN 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 polyethylene tubing. 6.2.4 Two burettes, of capacity 50

38、 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 of total nitrogen. 6.3.2 Determination 6.3.

39、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 occasional gentle swirling to ensure dissolution of

40、 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 cupboard with the heat input regulated to pass

41、 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 used instead of the digestion (6.3.2.3) if i

42、t 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-shaped hollow glass stopper into the neck of

43、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 been involving for at least 15 min. Allow the

44、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 fertilizers of unknown composition. Place the f

45、lask 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 BS EN 15750:2009EN 15750:2009 (E) 10 anti-foaming agent (6.1.3) to reduce foaming. Insert

46、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 7,5 min boil test (see 6.3.2.1, NOTE 2). If considerable foaming occurs, reduce the heat input until this phase is over. Continue to heat the flask and conten

47、ts until dense white fumes are cleared from the bulb of the flask. Gently swirl the flask and continue digestion for a further 60 min or until the solution is clear, whichever is the longer. Allow the flask to cool to room temperature and carefully add 250 ml of water. Allow the flask to cool. 6.3.2

48、.4 Distillation If distillation from the round-bottomed flask is preferred, transfer the test portion (6.3.1) or the hydrolysed (6.3.2.2) or digested (6.3.2.3) solution to it quantitatively. Otherwise, place the test portion, or retain the solution, in the Kjeldahl flask. Place the anti-bumping gran

49、ules or anti-bumping device (6.2.3), in the latter case with the polyethylene in contact with the bottom of the flask, in the flask, and add a few of the glass beads (6.2.5). Assemble the apparatus as shown in Figure 1. Measure into the receiver (see (5) in Figure 1), according to the expected mass of nitrogen in the test portion, the appropriate volume shown in Table 1 of one of the sulfuric acid solutions (6.1.10, 6.1.11 or 6.1.12). Table 1 Expected mass of nitrogen Expected mass of nitrogen