Fertilizers - Determination of molybdenum in concentrations ≤ 10 % using spectrometry of a complex with ammonium thiocyanate

This document specifies the procedure for determination of total and water extractable molybdenum in fertilizers containing less than or equal to 10 % molybdenum. The extraction methods are specified in EN 260172 and/or EN 260176.

Düngemittel - Bestimmung von Molybdän in Konzentrationen ≤ 10 % durch Spektrometrie eines Komplexes mit Ammoniumthiocyanat

Diese Europäische Norm legt ein Verfahren zur Bestimmung von Gesamtmolybdän und von wasserextrahierbarem Molybdän in mineralischen Düngemitteln, die weniger als oder gleich 10 % Molybdän enthalten, fest.
Dieses Verfahren ist auf Wasser  und Königswasser Extrakte von Düngemitteln anwendbar, die nach EN 16962 und/oder EN 16964 erhalten wurden.

Engrais - Dosage du molybdène dans des concentrations ≤ 10 % par spectrométrie d'un complexe avec le thiocyanate d'ammonium

La présente Norme européenne spécifie une méthode pour le dosage du molybdène total et du molybdène extractible à l’eau dans des engrais minéraux contenant au plus 10 % de molybdène.
Cette méthode est applicable aux extraits d’engrais aqueux et à l’eau régale obtenus conformément à l’EN 16962 et/ou à l’EN 16964.

Gnojila - Določevanje molibdena v koncentracijah, manjših ali enakih 10 %, s spektrometrijo kompleksa z amonijevim tiocianatom

Ta dokument določa postopek za določevanje skupne vsebnosti molibdena in molibdena, ki ga je mogoče ekstrahirati z vodo, v mineralnih gnojilih, ki vsebujejo manj kot oziroma 10 % molibdena. Metode ekstrahiranja so določene v standardu EN 260172 in/ali EN 260176.

General Information

Status
Published
Public Enquiry End Date
08-Nov-2016
Publication Date
09-Jul-2018
Technical Committee
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
22-Jun-2018
Due Date
27-Aug-2018
Completion Date
10-Jul-2018

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2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.XUFK65.080GnojilaFertilizersICS:Ta slovenski standard je istoveten z:EN 17043:2018SIST EN 17043:2018en,fr,de01-september-2018SIST EN 17043:2018SLOVENSKI

STANDARD
SIST EN 17043:2018
EUROPEAN STANDARD NORME EUROPÉENNE EUROPÄISCHE NORM
EN 17043
June
t r s z ICS
x wä r z r English Version
Fertilizers æ Determination of molybdenum in concentrations ≤
s r

¨ using spectrometry of a complex with ammonium thiocyanate Engrais æ Dosage du molybdène dans des concentrations ≤

s r
¨ par spectrométrie d 5un complexe avec du thiocyanate d 5ammonium
Düngemittel æ Bestimmung von Molybdän in Konzentrationen ≤
s r

¨ durch Spektrometrie eines Komplexes mit Ammoniumthiocyanat This European Standard was approved by CEN on

t x February
t r s zä

egulations which stipulate the conditions for giving this European Standard the status of a national standard without any alterationä Upætoædate lists and bibliographical references concerning such national standards may be obtained on application to the CENæCENELEC Management Centre or to any CEN memberä

translation under the responsibility of a CEN member into its own language and notified to the CENæCENELEC Management Centre has the same status as the official versionsä

CEN members are the national standards bodies of Austriaá Belgiumá Bulgariaá Croatiaá Cyprusá Czech Republicá Denmarká Estoniaá Finlandá Former Yugoslav Republic of Macedoniaá Franceá Germanyá Greeceá Hungaryá Icelandá Irelandá Italyá Latviaá Lithuaniaá Luxembourgá Maltaá Netherlandsá Norwayá Polandá Portugalá Romaniaá Serbiaá Slovakiaá Sloveniaá Spainá Swedená Switzerlandá Turkey and United Kingdomä

EUROPEAN COMMITTEE FOR STANDARDIZATION COMITÉ EUROPÉEN DE NORMALISATION EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre:
Rue de la Science 23,
B-1040 Brussels

t r s z CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Membersä Refä Noä EN

s y r v uã t r s z ESIST EN 17043:2018
EN 17043:2018 (E) 2 Contents Page

European foreword ....................................................................................................................................................... 3 Introduction .................................................................................................................................................................... 4 1 Scope .................................................................................................................................................................... 5 2 Normative references .................................................................................................................................... 5 3 Terms and definitions ................................................................................................................................... 5 4 Principle ............................................................................................................................................................. 5 5 Sampling and sample preparation ............................................................................................................ 5 6 Reagents ............................................................................................................................................................. 5 7 Apparatus ........................................................................................................................................................... 7 8 Procedure........................................................................................................................................................... 7 8.1 Preparation of calibration solutions ........................................................................................................ 7 8.2 Preparation of the test solutions ............................................................................................................... 7 8.3 Development and separation of the complex ....................................................................................... 7 8.4 Measurement .................................................................................................................................................... 8 9 Calculation and expression of the result ................................................................................................ 8 10 Test report ......................................................................................................................................................... 8 Annex A (informative)

Verification data – Comparison of ICP-AES method and spectrophotometric method with ammonium thiocyanate ......................................................... 10 A.1 Introduction ................................................................................................................................................... 10 A.2 Validation based on water extraction................................................................................................... 10 A.2.1 Test materials used in the validation study ....................................................................................... 10 A.2.2 Results of the validation study ................................................................................................................ 11 A.2.3 Conclusions .................................................................................................................................................... 12 A.3 Validation based on aqua regia extraction ......................................................................................... 12 A.3.1 Test materials used in the validation study ....................................................................................... 12 A.3.2 Comparison of ICP-AES and spectrophotometry .............................................................................. 14 A.3.3 Comparison of HCl- and aqua regia extraction .................................................................................. 15 A.3.4 Conclusions .................................................................................................................................................... 16 Bibliography ................................................................................................................................................................. 17

SIST EN 17043:2018

EN 17043:2018 (E) 3 European foreword This document (EN 17043:2018) 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 identical text or by endorsement, at the latest by December 2018, and conflicting national 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 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 organisations of the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, 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 United Kingdom. SIST EN 17043:2018

EN 17043:2018 (E) 4 Introduction The 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 Regulation (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 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 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. WARNING — 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 ensure 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. SIST EN 17043:2018

EN 17043:2018 (E) 5 1 Scope This European Standard specifies a method for determination of total 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 references The following documents, in whole or in part, are normatively 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 sample preparation - Part 2: Sample preparation EN 12944-1, Fertilizers and liming materials and soil improvers - Vocabulary - Part 1: General terms EN 12944-2, Fertilizers and liming materials and soil improvers - Vocabulary - Part 2: Terms relating to fertilizers EN 16962, Fertilizers - Extraction of water soluble micro-nutrients in fertilizers and removal of organic compounds from fertilizer extracts EN 16964, Fertilizers - Extraction of total micro-nutrients in fertilizers using aqua regia EN ISO 3696, Water for analytical laboratory use - Specification and test methods (ISO 3696) 3 Terms and definitions For the purposes of this document, the terms and definitions given in EN 12944-1 and EN 12944-2 apply. 4 Principle Molybdenum 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-orange coloured complex is determined spectrophotometrically at 470 nm. 5 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 [2]. Sample preparation shall be carried out in accordance with EN 1482-2. The sample extracts shall be prepared in accordance with EN 16962 and/or EN 16964. 6 Reagents All 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 ISO 3696 and free from molybdenum. SIST EN 17043:2018

EN 17043:2018 (E) 6 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 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 sulfate (CuSO4 5H2O) 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 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 with 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 the preparation of 100 ml of solution, dissolve 5 g of (SnCl2 2H2O) 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 [(NH4)6Mo7O24 4H2O] 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 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 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. SIST EN 17043:2018

EN 17043:2018 (E) 7 7 Apparatus 7.1 Spectrophotometer, 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 Procedure 8.1 Preparation of calibration solutions Prepare 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 acid (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 acid (6.2.1). 8.2 Preparation of the test solutions Dilute 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 according 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). Prepare a blank solution following the same procedure, omitting only the test sample of fertilizer. 8.3 Development and separation of the complex To 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 solution (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; after the separation of

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