EN 17043-2018 en Fertilizers - Determination of molybdenum in concentrations 10 % using spectrometry of a complex with ammonium thiocyanate.pdf

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1、BSI Standards PublicationWB11885_BSI_StandardCovs_2013_AW.indd 1 15/05/2013 15:06Fertilizers - Determination of molybdenum in concentrations 10 % using spectrometry of a complex with ammonium thiocyanateBS EN 17043:2018National forewordThis British Standard is the UK implementation of EN 17043:2018.

2、The UK participation in its preparation was entrusted to Technical Committee CII/37, Fertilisers and related chemicals.A list of organizations represented on this committee can be obtained on request to its secretary.This publication does not purport to include all the necessary provisions of a cont

3、ract. Users are responsible for its correct application. The British Standards Institution 2018 Published by BSI Standards Limited 2018ISBN 978 0 580 92805 5ICS 65.080Compliance with a British Standard cannot confer immunity from legal obligations.This British Standard was published under the author

4、ity of the Standards Policy and Strategy Committee on 30 June 2018.Amendments/corrigenda issued since publicationDate Text affectedBRITISH STANDARDBS EN 17043:2018EUROPEAN STANDARDNORME EUROPENNEEUROPISCHE NORMEN 17043June 2018ICS 65.080EUROPEAN COMMITTEE FOR STANDARDIZATIONCOMIT EUROPEN DE NORMALIS

5、ATIONEUROPISCHES KOMITEE FR NORMUNGCEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels 2018 CEN Ref. No. EN 17043:2018: EAll rights of exploitation in any form and by any means reserved worldwide for CEN national MembersFertilizers - Determination of molybdenum in concentrations 10 % us

6、ing spectrometry of a complex with ammonium thiocyanateEngrais - Dosage du molybdne dans des concentrations 10 % par spectromtrie dun complexe avec du thiocyanate dammoniumDngemittel - Bestimmung von Molybdn in Konzentrationen 10 % durch Spektrometrie eines Komplexes mit AmmoniumthiocyanatThis Europ

7、ean Standard was approved by CEN on 26 February 2018.CEN members are bound to comply with the CEN/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 co

8、ncerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to 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 i

9、nto its own language and notified to the CEN-CENELEC Management Centre has the same status as the official versions.CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France,

10、Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United Kingdom.English VersionEN 17043:2018 (E)European foreword iiiIntroduction iv1 Scope . 52

11、Normative references 53 Terms and definitions . 54 Principle 55 Sampling and sample preparation 56 Reagents 57 Apparatus .78 Procedure.78.1 Preparation of calibration solutions . 78.2 Preparation of the test solutions . 78.3 Development and separation of the complex . 78.4 Measurement 89 Calculation

12、 and expression of the result .810 Test report .8Annex A (informative) Verification data Comparison of ICP-AES method and spectrophotometric method with ammonium thiocyanate .10Bibliography .16iiContents PageBS EN 17043:2018EN 17043:2018 (E)European forewordThis document (EN 17043:2018) has been pre

13、pared 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 endorsement, at the latest by December 2018, and conflicting n

14、ational standards shall be withdrawn at the latest by December 2018.Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CEN shall not be held responsible for identifying any or all such patent rights.This document has been prepared un

15、der 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 organisations of the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus,

16、 Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the U

17、nited Kingdom.iiiBS EN 17043:2018EN 17043:2018 (E)IntroductionThe preparation of this document by CEN is based on a mandate by the European Commission and the European Free Trade Association (Mandate M/335), concerning the modernization of methods of analysis of fertilizers in the framework of Regul

18、ation (EC) No 2003/2003 1.This European Standard is part of a modular approach and concerns the analytical measurement step. “Modular” means that a test standard concerns a specific step in assessing a property and not the whole chain of measurement.The determination of molybdenum in fertilizers can

19、 be executed by inductively coupled plasma-atomic emission spectrometry (ICP-AES) according to EN 16963. The spectrophotometric determination of the complex with ammonium thiocyanate is more labour intensive and skill demanding but it is an option when ICP-AES is not available. More attention should

20、 be paid to organic matter removal and interferences from extract colour. The procedure for removal of organic matter from the extracts is specified in EN 16962, which also describes the modification of the extraction procedure using acidification with hydrochloric acid instead of nitric acid.WARNIN

21、G Persons using this European Standard should be familiar with normal laboratory practice. This European Standard does not purport to address all of the safety issues, if any, associated with its use. It is the responsibility of the user to establish appropriate health and safety practices and to en

22、sure compliance with any national regulatory conditions. IMPORTANT It is absolutely essential that tests conducted according to this European Standard are carried out by suitably trained staff. ivBS EN 17043:2018EN 17043:2018 (E)1 ScopeThis European Standard specifies a method for determination of t

23、otal and water extractable molybdenum in mineral fertilizers containing less than or equal to 10 % molybdenum.This method is applicable to water and aqua regia fertilizer extracts obtained according to EN 16962 and/or EN 16964.2 Normative referencesThe following documents, in whole or in part, are n

24、ormatively referenced in this document and are indispensable for its application. 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 sa

25、mple preparation Part 2: Sample preparationEN 12944-1, Fertilizers and liming materials and soil improvers Vocabulary Part 1: General termsEN 12944-2, Fertilizers and liming materials and soil improvers Vocabulary Part 2: Terms relating to fertilizersEN 16962, Fertilizers Extraction of water soluble

26、 micro-nutrients in fertilizers and removal of organic compounds from fertilizer extractsEN 16964, Fertilizers Extraction of total micro-nutrients in fertilizers using aqua regiaEN ISO 3696, Water for analytical laboratory use Specification and test methods (ISO 3696)3 Terms and definitionsFor the p

27、urposes of this document, the terms and definitions given in EN 12944-1 and EN 12944-2 apply.4 PrincipleMolybdenum Mo(V) forms a complex MoO(SCN)5 in an acid medium with SCN-ions. The complex is extracted into n-butyl acetate. Interfering ions such as iron remain in the aqueous phase. The yellow-ora

28、nge coloured complex is determined spectrophotometrically at 470 nm.5 Sampling and sample preparationSampling is not part of the method specified in this document. A recommended sampling method is given in EN 1482-1 2.Sample preparation shall be carried out in accordance with EN 1482-2. The sample e

29、xtracts shall be prepared in accordance with EN 16962 and/or EN 16964.6 ReagentsAll reagents shall be of recognized analytical grade and shall have negligible concentration of molybdenum if compared to the lowest concentration of that element in the sample solution.6.1 Water, grade 2 according to EN

30、 ISO 3696 and free from molybdenum.5BS EN 17043:2018EN 17043:2018 (E)6.2 Hydrochloric acid, (HCl) 37 %, = 1,18 g/ml.6.2.1 Diluted hydrochloric acid solution, with a concentration of about 6 mol/l.Mix one volume of hydrochloric acid (6.2) with one volume of water (6.1).6.2.2 Diluted hydrochloric acid

31、 solution, with a concentration of about 0,5 mol/l.Add 42 ml of hydrochloric acid (6.2) to approximately 600 ml of water (6.1) in a 1 000 ml volumetric flask (7.4). Fill to the mark with water (6.1) after cooling.6.3 Copper solution, = 70 mg/l in 1,5 mol/l hydrochloric acid.Dissolve 275 mg of copper

32、 sulfate (CuSO45H2O) weighed to within 0,1 mg in 250 ml of the 6 mol/l hydrochloric acid solution (6.2.1) in a 1 000 ml volumetric flask (7.4). Make up to volume with water (6.1) and mix thoroughly.6.4 Ascorbic acid solution, = 50 g/l.Dissolve 50 g of ascorbic acid (C6H8O6) in water (6.1) in a 1 000

33、 ml volumetric flask (7.4). Make up to volume with water (6.1), mix thoroughly and keep in a refrigerator.6.5 n-butyl acetate.6.6 Ammonium thiocyanate solution, c = 0,2 mol/l.Dissolve 15,224 g of ammonium thiocyanate (NH4SCN) in water (6.1) in a 1 000 ml volumetric flask (7.4). Make up to volume wit

34、h water (6.1), mix thoroughly and store in a dark-coloured bottle.6.7 Stannous chloride solution, = 50 g/l in 2 mol/l hydrochloric acid.This solution shall be perfectly clear and prepared immediately before use. Very pure stannous chloride shall be used otherwise the solution will not be clear.For t

35、he preparation of 100 ml of solution, dissolve 5 g of (SnCl22H2O) in 35 ml of 6 mol/l hydrochloric acid solution (6.2.1). Add 10 ml of the copper solution (6.3). Make up to volume with water (6.1) and mix thoroughly.6.7.1 Molybdenum stock solution, = 1 000 mg/l.Dissolve 1,840 g of ammonium molybdate

36、 (NH4)6Mo7O244H2O weighed to within 0,1 mg in the 0,5 mol/l hydrochloric acid (6.2.2) in a 1 000 ml volumetric flask (7.4). Make up to volume with that solution and mix thoroughly.Commercially available stock solutions with adequate specification may be used. The solution is considered to be stable

37、for more than one year, but in reference to guaranteed stability, the recommendations of the manufacturer shall be considered.6.7.2 Molybdenum intermediate solution, = 100 mg/l.Place 10 ml of the stock solution (6.7.1) in a 100 ml volumetric flask (7.3). Make up to volume with 0,5 mol/l hydrochloric

38、 acid (6.2.2) and mix thoroughly.6.7.3 Molybdenum working solution, = 10 mg/l.Place 10 ml of the intermediate solution (6.7.2) in a 100 ml volumetric flask (7.3). Make up to volume with 0,5 mol/l hydrochloric acid (6.2.2) and mix thoroughly.6 BS EN 17043:2018EN 17043:2018 (E)7 Apparatus7.1 Spectroph

39、otometer, set to a wavelength of 470 nm with a cuvette with a 10 mm optical path.7.2 Separating funnels, capacity 200 ml or 250 ml.7.3 Volumetric flasks, capacity 100 ml.7.4 Volumetric flasks, capacity 1 000 ml.7.5 Precision pipette.7.6 Test tube.8 Procedure8.1 Preparation of calibration solutionsPr

40、epare a series of at least six calibration solutions of increasing concentration corresponding to the optimum response range of the spectrometer.Pipette 0 ml, 1 ml, 2 ml, 3 ml, 4 ml and 5 ml of working solution (6.7.3) into 100 ml volumetric flasks (7.3), fill to the mark with diluted hydrochloric a

41、cid (6.2.2) and mix well. The calibration solutions contain mass concentrations of respectively Mo = 0 mg/l; Mo = 0,1 mg/l; Mo = 0,2 mg/l; Mo = 0,3 mg/l; Mo = 0,4 mg/l and Mo = 0,5 mg/l.Pipette 25 ml of calibration solutions into the separating funnels (7.2) and add 25 ml of 6 mol/l hydrochloric aci

42、d (6.2.1).8.2 Preparation of the test solutionsDilute an aliquot portion of the aqua regia extracts prepared according to EN 16964 five times with water (6.1) to achieve final concentration of acids approximately 0,5 mol/l. The final concentration of hydrochloric acid in water extracts prepared acco

43、rding to EN 16962 is 0,5 mol/l. Dilute these solutions with 0,5 mol/l hydrochloric acid (6.2.2) if necessary to obtain a molybdenum concentration in the range specified in (8.1). Pipette 25 ml of the test solutions into the separating funnels (7.2) and add 25 ml of 6 mol/l hydrochloric acid (6.2.1).

44、Prepare a blank solution following the same procedure, omitting only the test sample of fertilizer.8.3 Development and separation of the complexTo the separating funnels containing the calibration solutions (8.1), test solutions (8.2) and blank (8.2), add in the following order:10 ml of the copper s

45、olution (6.3); 20 ml of the ascorbic acid solution (6.4); mix thoroughly and wait for 2 min to 3 min.Then add 10 ml of n-butyl acetate (6.5), using a precision pipette (7.5); 20 ml of the thiocyanate solution (6.6). Shake for 1 min to extract the complex in the organic phase; allow to precipitate; a

46、fter the separation of the two phases, draw off the entire aqueous phase and discard it.Then wash the organic phase with 10 ml of the stannous chloride solution (6.7). Shake for 1 min. Allow to precipitate and draw off the entire aqueous phase. Collect the organic phase in a test tube (7.6); this wi

47、ll make it possible to collect the drops of water in suspension.7BS EN 17043:2018EN 17043:2018 (E)8.4 MeasurementMeasure the absorbance of each of the solutions obtained in (8.3) against 0 mg/l molybdenum calibration solution (8.1) as a reference at a wavelength of 470 nm in a 10 mm cuvette using th

48、e spectrophotometer (7.1). Rinse the cuvette using the following solution before each reading.The calibration solutions are equivalent to mass concentrations of Mo = 0 mg/l; Mo = 0,25 mg/l; Mo = 0,5 mg/l; Mo = 0,75 mg/l; Mo = 1 mg/l and Mo = 1,25 mg/l. These concentrations are used for the calculati

49、on of a calibration curve (usually by the software of the spectrophotometer). Read the concentration of molybdenum in the test solutions in mg/l.If low molybdenum content is to be determined, a cuvette having 20 mm or 50 mm optical path and adequately adapted calibration range is recommended.9 Calculation and expression of the resultCalculate the content of molybdenum in the sample by reference to the calibration curve and taking into consideration the blank.Calculate the content of molybdenum in the fertilizer, wX, as a mas