BS EN 15477-2009 Fertilizers - Determination of the water-soluble potassium content《肥料 水溶性钾含量的测定》.pdf

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1、BS EN 15477:2009ICS 65.080NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBRITISH STANDARDFertilizers Determination ofthe water-solublepotassium contentThis British Standardwas published under theauthority of the StandardsPolicy and StrategyCommittee on 28 February2009 BSI 2009

2、ISBN 978 0 580 62383 7Amendments/corrigenda issued since publicationDate CommentsBS EN 15477:2009National forewordThis British Standard is the UK implementation of EN 15477:2009. Itsupersedes DD CEN/TS 15477:2006 which is withdrawn.The UK participation in its preparation was entrusted to TechnicalCo

3、mmittee 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.Compliance with

4、 a British Standard cannot confer immunityfrom legal obligations.BS EN 15477:2009EUROPEAN STANDARDNORME EUROPENNEEUROPISCHE NORMEN 15477January 2009ICS 65.080 Supersedes CEN/TS 15477:2006 English VersionFertilizers - Determination of the water-soluble potassiumcontentEngrais - Dtermination de la ten

5、eur en potassium solubledans leauDngemittel - Bestimmung von wasserlslichem KaliumThis 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 n

6、ational 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 official versions (English, French, German). A version in

7、 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, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Es

8、tonia, 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 FOR STANDARDIZATIONCOMIT EUROPEN DE NORMALISATIONEUROPIS

9、CHES 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 15477:2009: EBS EN 15477:2009EN 15477:2009 (E) 2 Contents Page Foreword 3 1 Scope 4 2 Normative refere

10、nces 4 3 Terms and definitions .4 4 Principle 4 5 Reagents .4 6 Apparatus .5 7 Sampling and sample preparation .5 8 Procedure .5 9 Calculation and expression of the result 7 10 Precision .8 11 Test report 9 Annex A (informative) Results of the inter-laboratory tests 10 Bibliography . 11 BS EN 15477:

11、2009EN 15477:2009 (E) 3 Foreword This document (EN 15477:2009) 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 identic

12、al 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 patent rights. CEN and/or CENELEC shall not be held responsi

13、ble for identifying any or all such patent rights. This document supersedes CEN/TS 15477:2006. 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 or

14、ganizations 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, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,

15、 Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and the United Kingdom. BS EN 15477:2009EN 15477:2009 (E) 4 1 Scope This European Standard specifies a method for the determination of water-soluble potassium, which is applicable to all potassium fertilizers listed in Annex I of the Regulatio

16、n (EC) No 2003/2003 3. 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

17、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 1: General terms EN 12944-2:1999, Fertilizers and liming materials and soil improvers Vocabulary Part 2: Terms rela

18、ting 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 terms and definitions given in EN 12944-1:1999 and EN 12944-2:1999 apply. 4 Principle The potassium in the sample to

19、 be analyzed is dissolved in water. After eliminating or fixing the substances that might interfere with the quantitative determination, the potassium is precipitated in a slightly alkaline medium in the form of potassium tetraphenylborate. 5 Reagents 5.1 General Use only reagents of recognized anal

20、ytical grade and distilled or demineralized water (grade 3 according to EN ISO 3696:1995). 5.2 Formaldehyde, clear formaldehyde solution with a mass fraction of 25 % to 35 % formaldehyde. 5.3 Potassium chloride, p. a. 5.4 Sodium hydroxide solution, c = 10 mol/l. Care should be taken to ensure that o

21、nly potassium free sodium hydroxide is used. 5.5 Indicator solution Dissolve 0,5 g of phenolphthalein in ethanol at 90 % and make the volume up to 100 ml. BS EN 15477:2009EN 15477:2009 (E) 5 5.6 EDTA solution Dissolve 4 g of the dihydrated disodium salt of ethylenediaminetetraacetic acid in water in

22、 a 100 ml graduated flask. Make up the volume and mix. Store the reagent in a plastics container. 5.7 STPB solution Dissolve 32,5 g of sodium tetraphenylborate in 480 ml of water, add 2 ml of the sodium hydroxide solution (5.4) and 20 ml of a magnesium chloride solution (100 g of MgCl26H2O per litre

23、). Stir for 15 min and filter through a fine, ashless filter. Store this reagent in a plastics container. 5.8 Liquid for washing Dilute 20 ml of the STPB solution (5.7) to 1 000 ml with water. 5.9 Bromine water, saturated bromine solution in water. 6 Apparatus 6.1 Graduated flasks, capacity 1 000 ml

24、. 6.2 Beaker, capacity 250 ml and 600 ml. 6.3 Filter crucibles, porosity 5 m to 20 m. 6.4 Oven, regulated at (120 10) C. 6.5 Desiccator 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 prepara

25、tion shall be carried out in accordance with EN 1482-2. Grinding is recommended for homogeneity reasons. 8 Procedure 8.1 Test portion Weigh to the nearest 0,001 g 10 g of the prepared sample (5 g for potassium salts with a mass fraction of potassium oxide of more than 50 %). Place this test portion

26、in a 600 ml beaker with approximately 400 ml of water. Bring to a boil and allow it to boil for 30 min. Cool, transfer quantitatively into a 1 000 ml graduated flask, make up the volume, mix and filter into a dry receiver. Discard the first 50 ml of the filtrate (see 8.6). BS EN 15477:2009EN 15477:2

27、009 (E) 6 8.2 Preparation of the aliquot part for precipitation Transfer by pipette an aliquot part of the filtrate containing 25 mg to 50 mg of potassium (see Table 1) and place it in a 250 ml beaker. If required make up to 50 ml with water. To remove any interference, add 10 ml of the EDTA solutio

28、n (5.6), several drops of the phenolphthalein solution (5.5) and stir in, drop by drop, sodium hydroxide solution (5.4) until it turns red, then finally add a few more drops of sodium hydroxide to ensure an excess (usually 1 ml of sodium hydroxide is sufficient to neutralize the sample and ensure an

29、 excess). To eliminate most of the ammonia, (see 8.6) boil gently for 15 min. If necessary, add water to make the volume up to 60 ml. Bring the solution to the boil, remove the beaker from the heat and add 10 ml of formaldehyde (5.2). Add several drops of phenolphthalein and, if necessary, some more

30、 sodium hydroxide until a distinct red colour appears. Cover the beaker with a watch glass and place it on a steam bath for 15 min. 8.3 Weighing the crucible Dry the filter crucible to a constant mass (about 15 min) in the oven at 120 C. Allow the crucible to cool in a desiccator and then weigh it.

31、8.4 Precipitation Remove the beaker from the steam bath, stir in drop-by-drop 10 ml of the STPB solution (5.7). This addition takes about 2 min. Wait for at least 10 min before filtering. 8.5 Filtering and washing Filter under vacuum into the weighed crucible, rinse the beaker with the liquid for wa

32、shing (5.8), wash the precipitate three times with the liquid for washing (60 ml in all of the liquid for washing), and twice with 5 ml to 10 ml of water. Dry the precipitate thoroughly. 8.6 Drying and weighing Wipe the outside of the crucible with a filter paper. Place the crucible with its content

33、s in the oven for 1,5 h at 120 C. Allow the crucible to cool in a desiccator to ambient temperature and weigh immediately. If the filtrate is dark in colour, transfer by pipette, an aliquot part containing at the most, 100 mg of K2O and place in a 100 ml graduated flask. Add bromine water (5.9) and

34、bring to a boil to eliminate any surplus bromine. After cooling make up the volume, filter and quantitatively determine the potassium in an aliquot part of the filtrate. Where there is little or no ammoniacal nitrogen present there is no need to boil for 15 min. BS EN 15477:2009EN 15477:2009 (E) 7 8

35、.7 Aliquot parts to be taken as samples and conversion factors Table 1 Aliquot parts and conversion factors K2O in the fertilizer % K in the fertilizer % Sample for analysis g Sample of the extract solution for the dilution ml Dilution to ml Aliquot part to be taken as a sample for precipitation ml

36、Conversion factor F TPBKgOK% 2Conversion factor F TPBKgK%5 - 10 4,2 8,3 10 - - 50 26,280 21,812 10 - 20 8,3 16,6 10 - - 25 52,560 43,624 20 - 50 16,6 41,5 10 either or 50 250 10 50 131,400 131,400 109,060 109,060 more than 50 more than 41,5 5 either or 50 - 250 10 50 262,800 262,800 218,120 218,120

37、8.8 Blank test For each series of determinations, carry out a blank test using only the reagents in the proportions used in the analysis and allow for this when calculating the final result. 8.9 Control test In order to obtain a control for the Method of analysis, carry out a determination on an ali

38、quot part of an aqueous solution of potassium chloride, containing at the most 40 mg of K2O. 9 Calculation and expression of the result 9.1 Dilution according to Table 1 Calculate the K2O content, OK2w , as mass fraction in percent of the fertilizer according to equation (1): Fmmw = )(21OK2(1) Calcu

39、late the K content, wK, as mass fraction in percent of the fertilizer according to equation (2): )(21KFmmw = (2) where m1is the mass of the precipitate from the sample, in grams; m2is the mass of the precipitate from the blank, in grams; F and F conversion factors (see Table 1). BS EN 15477:2009EN 1

40、5477:2009 (E) 8 9.2 Dilution different from Table 1 Calculate the K2O content, OK2w , as mass fraction in percent of the fertilizer according to equation (3): mDFmmw100212=)(OK(3) Calculate the K content, wK, as mass fraction in percent of the fertilizer according to equation (4): mDFmmw10021=)(K(4)

41、 where m1is the mass of the precipitate from the sample, in grams; m2is the mass of the precipitate from the blank, in grams; F conversion factor, KTPB into K2O = 0,1314; F conversion factor, KTPB into K = 0,109; D dilution factor; m is the mass of the sample for analysis (test portion), in grams. 1

42、0 Precision 10.1 Inter-laboratory test An inter-laboratory test was carried out in 2004 with 16 participating laboratories and two different samples of fertilizers and phosphate types. This test yielded the data given in Annex A. Repeatability and reproducibility were calculated according to ISO 572

43、5-1. The values derived from this inter-laboratory test might not be applicable to concentration ranges and matrices other than those given in Annex A. 10.2 Repeatability The absolute difference between two independent single test results, obtained with the same method on identical test material in

44、the same laboratory by the same operator using the same equipment within a short interval of time, will in not more than 5 % of the cases exceed the values of r given in Table 2. 10.3 Reproducibility The absolute difference between two single test results, obtained with the same method on identical

45、test material in different laboratories by different operators using different equipment, will in not more than 5 % of the cases exceed the values of R given in Table 2. BS EN 15477:2009EN 15477:2009 (E) 9 Table 2 Mean values, repeatability and reproducibility limits Sample x % r % R % NPK1 (14-8-24

46、+8S) 24,66 0,26 0,71 NPK2 (16-16-8+4S) 8,18 0,12 0,32 11 Test report The test report shall contain at least the following information: a) all information necessary for the complete identification of the sample; b) test method used with reference to this document; c) test results obtained; d) date of

47、 sampling and sampling procedure (if known); e) date when the analysis was finished; f) whether the requirement of the repeatability limit has been fulfilled; g) all operating details not specified in this document, or regarded as optional, together with details of any incidents occurred when perfor

48、ming the method which might have influenced the test result(s). BS EN 15477:2009EN 15477:2009 (E) 10 Annex A (informative) Results of the inter-laboratory tests The precision of the method was established in 2004 by Working Group 7 “Chemical analysis” of CEN/TC 260 “Fertilizers and liming materials”

49、 in an inter-laboratory test evaluated in accordance with ISO 5725-1. The statistical results are given in Table A.1. Table A.1 Statistical results of the inter-laboratory test Parameter Sample NPK1 (14-8-24+8S) NPK2 (16-16-8+4S) Number of participating laboratories 16 16 Number of laboratories after elimination of outliers (accepted test results) 13 14Mean value x (%) 24,66 8,18 Repeatability standard deviation sr(%) 0,09 0,04RSDr (%) 0,4 0,5 Repeatability limit r (%) 0,26 0,12Reproducibility standard deviation sR(%)