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STANDARDSIST-TS CEN/TS 15451:20081DGRPHãþD
SIST EN 15451:2009
EUROPEAN STANDARDNORME EUROPÉENNEEUROPÄISCHE NORMEN 15451July 2008ICS 65.080Supersedes CEN/TS 15451:2006
English VersionFertilizers - Determination of chelating agents - Determination ofiron chelated by EDDHSA by ion pair chromatographyEngrais - Dosage des agents chélatants - Dosage du ferchélaté par EDDHSA par chromatographie d'appariementd'ionsDüngemittel - Bestimmung von Chelatbildnern -Bestimmung von Eisen-chelatisiertem EDDHSA mit Ionen-PaarchromatographieThis European Standard was approved by CEN on 30 May 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 national 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 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, Estonia, 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 STANDARDIZATIONCOMITÉ EUROPÉEN DE NORMALISATIONEUROPÄISCHES KOMITEE FÜR NORMUNGManagement Centre: rue de Stassart, 36
B-1050 Brussels© 2008 CENAll rights of exploitation in any form and by any means reservedworldwide for CEN national Members.Ref. No. EN 15451:2008: ESIST EN 15451:2009
EN 15451:2008 (E) 2 Contents Page Foreword.3 1 Scope.4 2 Normative references.4 3 Principle.4 4 Interferences.4 5 Reagents.4 6 Apparatus.5 7 Sampling and sample preparation.6 8 Procedure.7 9 Expression of the result.7 10 Precision for Fe3+/EDDHSA.8 11 Test report.8 Annex A (informative)
Chromatogram for Fe3+/EDDHSA.10 Annex B (informative)
Spectra UV-visible for Fe3+/EDDHSA.11 Annex C (informative)
Results of the inter-laboratory tests.12 Annex D (informative)
Complete names of chelating agents.14 Bibliography.15
SIST EN 15451:2009
EN 15451:2008 (E) 3 Foreword This document (EN 15451:2008) 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 January 2009, and conflicting national standards shall be withdrawn at the latest by January 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 responsible for identifying any or all such patent rights. This document supersedes CEN/TS 15451:2006. 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 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, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and the United Kingdom. SIST EN 15451:2009
EN 15451:2008 (E) 4 1 Scope This European Standard specifies a method for the chromatographic determination of the total amount of iron chelated by EDDHSA in commercial products. 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, Fertilizers and liming materials — Sampling and sample preparation — Part 2: Sample preparation EN ISO 3696:1995, Water for analytical laboratory use — Specification and test methods (ISO 3696:1987) 3 Principle The iron chelates are determined by ion-pair high-performance liquid chromatography. When an iron chelate (anion) is added to a polar fluid (eluent), containing a large cation (ion-pair reagent), an ion pair is formed. This ion pair is retained by an apolar solid phase (stationary phase). The strength of the retention depends on the molecular size and its acidity. Each iron chelate presents a characteristic retention time and a characteristic spectrum depending on the chelating agent, and it is separated from the other substances present in the sample. The separation is carried out on a reverse phase silica column and an aqueous solution of TBA+ (tetrabutylammonium) and acetonitrile as eluent. The detection is based on photometry at 480 nm. For Fe3+/EDDHSA a gradient method is required. 4 Interferences No interferences have been detected. Iron chelates with o,o-EDDHA, o,p-EDDHA, o,o-EDDHMA, EDTA, DTPA, CDTA, HEDTA, as well as the chelating agents do not interfere since they are separated from Fe3+/EDDHSA. 5 Reagents 5.1 General a) All reagents shall be of recognized analytical grade. b) All water used for the preparation of eluent, standards, and sample solutions should be water grade1 according to EN ISO 3696:1995. c) When reagents with a declared purity of less than 99 % are used for the preparation of standard solutions, a correction should be made in order to obtain the required concentration in the solution. 5.2 Sodium hydroxide solution, c(NaOH) = 0,5 mol/l Dissolve 20 g of NaOH in pellet form in a 1 litre-volumetric flask with water free of carbon dioxide. Dilute to the mark and homogenize. 5.3 Sodium hydroxide solution, c(NaOH) = 0,1 mol/l Dissolve 4 g of NaOH in pellet form in a 1 litre volumetric flask with water free of carbon dioxide. Dilute to the mark and homogenize. SIST EN 15451:2009
EN 15451:2008 (E) 5 5.4 Hydrochloric acid solution, c(HCl) = 1,0 mol/l Dilute 88 ml of hydrochloric acid (35 % HCl) to 1 000 ml with water. 5.5 Hydrochloric acid solution, c(HCl) = 0,1 mol/l Dilute 50 ml of hydrochloric acid (5.4) to 500 ml with water. 5.6 Iron (III) nitrate solution, (Fe) = 1 050 mg/l Dissolve 0,7594 g of iron (III) nitrate nonahydrate [Fe(NO3)3·9H2O] in 100 ml of water. Transfer to a 100 ml-volumetric flask. Dilute to the mark with water and homogenize. Check (for example by AAS) that the Fe concentration of this solution is (1 050 ± 30) mg/l. As the Fe(NO3)3·9H2O is deliquescent, for preparation of the Fe3+/EDDHSA solution (5.7) it shall be added in solution of a known concentration. 5.7 Fe3+/EDDHSA solution, (Fe) = 100 mg/l Dissolve 0,233 0 g×100/P, where P is the complexometric purity of the standard in percentage of the acid form H6EDDHSA obtained by either manual or automatic photometric titration with a Fe(III)standard at constant pH = 6 (pH stat system), of ethylene diamine di(2-hydroxy-5-sulfophenyl) acetic acid and its condensation products (EDDHSA) in 150 ml of water and 2,7 ml of NaOH (5.2). After complete dissolution, add 25 ml of the Fe solution (5.6) to the chelating agent solution stirring about 5 min. The solution is adjusted to pH 7,0 with NaOH solution (5.3). Let the solution stand overnight in darkness to allow excess Fe to precipitate as oxide. Filter quantitatively through a cellulose filter and make up to volume (250 ml) with water. 5.8 Eluent for the determination Two solutions are used to make a linear gradient eluent: a) Solution A: Add 3,33 ml of TBAOH [40 % (mass fraction) Tetrabutylammonium hydroxide solution in water] to 500 ml of water. Adjust pH to 6,0 with HCl (5.4 and 5.5). Add 350 ml of acetonitrile (HPLC grade) and make up to volume in a 1 litre-volumetric flask with water. Filter through 0,2 µm membrane filter (6.4 b). b) Solution B: Add 3,33 ml of TBAOH [40 % (mass fraction) Tetrabutylammonium hydroxide solution in water] to 150 ml of water. Adjust pH to 6,0 with HCl (5.4 and 5.5). Add 750 ml of acetonitrile (HPLC grade) and make up to volume in a 1 litre-volumetric flask with water. F
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