SIST EN 15705:2024

SLOVENSKI STANDARD
01-junij-2024
Nadomešča:
SIST EN 15705:2010
Anorganska gnojila - Določanje oligomerov metilenuree s tekočinsko
kromatografijo visoke ločljivosti (HPLC)
Inorganic fertilizers - Determination of methylen-urea oligomers using high-performance
liquid chromatography (HPLC)
Anorganische Düngemittel - Bestimmung von Methylenharnstoff-Oligomeren mittels
Hochleistungsflüssigkeitschromatographie (HPLC)
Engrais inorganiques - Dosage des oligomères de méthylène-urée par chromatographie
liquide haute performance (HPLC)
Ta slovenski standard je istoveten z: EN 15705:2023
ICS:
65.080 Gnojila Fertilizers
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN 15705
EUROPEAN STANDARD
NORME EUROPÉENNE
December 2023
EUROPÄISCHE NORM
ICS 65.080 Supersedes EN 15705:2010
English Version
Inorganic fertilizers - Determination of methylen-urea
oligomers using high-performance liquid chromatography
(HPLC)
Engrais inorganiques - Dosage des oligomères de Anorganische Düngemittel - Bestimmung von
méthylène-urée par chromatographie liquide haute Methylenharnstoff-Oligomeren mittels
performance (HPLC) Hochleistungsflüssigkeitschromatographie (HPLC)
This European Standard was approved by CEN on 27 November 2023.

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
concerning 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 into 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, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and
United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2023 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 15705:2023 E
worldwide for CEN national Members.

Contents Page
European foreword . 3
1 Scope . 4
2 Normative references . 4
3 Terms and definitions . 4
4 Principle . 4
5 Reagents . 4
6 Apparatus and equipment . 5
7 Sampling and sample preparation . 5
8 Procedure . 5
8.1 Calibration . 5
8.1.1 Stock solution of urea, mass concentration ρ ≈ 1 000 mg/kg . 5
8.1.2 Stock solution of methylen-diurea, ρ ≈ 1 000 mg/kg . 6
8.1.3 Stock solution of dimethylen-triurea, ρ ≈ 1 000 mg/kg . 6
8.1.4 Stock solution of trimethylen-tetraurea, ρ ≈ 100 mg/kg. 6
8.1.5 Calibration solutions . 6
8.2 Preparation of the test solution . 7
8.3 Measurement . 7
9 Calculations and expression of the result . 7
10 Precision . 9
10.1 Inter-laboratory tests . 9
10.2 Repeatability . 9
10.3 Reproducibility . 9
11 Test report . 10
Annex A (informative) Results of the inter-laboratory tests. 11
Annex B (informative) Example chromatogram and calibration curves . 12
B.1 Example chromatogram . 12
B.2 Example calibration curves . 13
Annex C (informative) Example conditions for a suitable HPLC system . 15
Bibliography . 16
European foreword
This document (EN 15705:2023) 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 June 2024, and conflicting national standards shall be
withdrawn at the latest by June 2024.
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, together with EN 17864:2023, supersedes EN 15705:2010.
In comparison with EN 15705:2010, the following technical modifications have been made:
— EN 15705:2010 is split into two documents:
— Method A of EN 15705:2010 is given in EN 17864:2023;
— Method B of EN 15705:2010 is given in this document.
Any feedback and questions on this document should be directed to the users’ national standards body.
A complete listing of these bodies can be found on the CEN website.
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, France, Germany, Greece, Hungary, Iceland,
Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of
North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and the
United Kingdom.
1 Scope
This document specifies a method for the determination of methylen-urea (MU) oligomers in inorganic
fertilizers using high-performance liquid chromatography (HPLC).
The method is applicable to all fertilizers which do not contain interfering organic compounds.
NOTE By the condensation of urea and formaldehyde, several oligomers are formed, such as methylen–
diurea (MDU), dimethylen-triurea (DMTU), trimethylen-tetraurea (TMTU) and higher oligomers. The three
molecules named here are the most soluble in water, while the higher compounds are insoluble in hot water, but
their nitrogen is available for plants by microbiological decomposition. Also, urea is always a companion of MU-
oligomers.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements 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 12944-1, Fertilizers and liming materials — Vocabulary — Part 1: General terms
EN 12944-2, Fertilizers and liming materials — Vocabulary — Part 2: Terms relating to fertilizers
3 Terms and definitions
For the purposes of this document, the terms and definitions given in EN 12944-1 and EN 12944-2
apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— IEC Electropedia: available at https://www.electropedia.org/
— ISO Online browsing platform: available at https://www.iso.org/obp
4 Principle
The sample is extracted with boiling water and analysed using a suitable HPLC system.
The methylen-urea soluble oligomers are measured and detected by the HPLC-method.
In the chromatogram methylen-urea oligomers are represented by different peaks: urea, methylen-
diurea, dimethylen-triurea; trimethylen-tetraurea are, in the meantime, the most soluble and important.
5 Reagents
Use only reagents of recognized analytical grade and distilled or demineralized water, free from carbon
dioxide and all nitrogenous compounds and having an electric conductivity < 0,5 mS/m.
5.1 Acetonitrile, HPLC-grade.
5.2 Urea, p.a., mass fraction of 46,6 % of total nitrogen.
5.3 Methylen-diurea (MDU), synthesized and purified by a special laboratory , having a mass
fraction of 42,4 % of total nitrogen.
5.4 Dimethylen-triurea (DMTU), synthesized and purified by a special laboratory , having a mass
fraction of 41,2 % of total nitrogen.
5.5 Trimethylen-tetraurea (TMTU), synthesized and purified by a special laboratory, having a mass
fraction of 40,6 % of total nitrogen.
6 Apparatus and equipment
Usual laboratory glassware and equipment and, in particular, the following.
6.1 Analytical balance, capable for weighing to of the nearest 0,1 mg.
6.2 Technical balance, capable of weighing to of the nearest 0,01 g.
6.3 HPLC-system, equipped with an UV-detector.
An example of a suitable column and analytical conditions are reported in Annex C.
A guard-column is recommended.
An acceptable chromatogram, as shown as example in Annex B, can be achieved using the column and
analytical conditions reported in Annex C.
6.4 Ultrasonic bath.
6.5 Magnetic stirrer.
6.6 Disposable filter, 0,45 µm.
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 [1].
Sample preparation shall be carried out in accordance with EN 1482-2.
8 Procedure
8.1 Calibration
8.1.1 Stock solution of urea, mass concentration ρ ≈ 1 000 mg/kg
Weigh 100/P mg of urea (5.2), where P is the purity of urea expressed as a pure number, to the nearest
0,1 mg and put into an empty and dry 100 ml volumetric flask, weighed before to the nearest 0,01 g.
Add 50 ml of water and dissolve the urea in an ultrasonic bath (6.4) for about 10 min. Make up
approximately to the mark with water and homogenize. Weigh the full flask to the nearest 0,01 g and
record the net mass. Store at room temperature, well closed. This stock solution is stable for one week.

The standard substances MDU and DMTU can be prepared according to the method given in Official Methods of
Analysis of AOAC International, AOAC Official Method 983.01, JAOAC 66, 769 (1983) [5].
8.1.2 Stock solution of methylen-diurea, ρ ≈ 1 000 mg/kg
Weigh 50/P mg of MDU (5.3), where P is the purity of MDU expressed as a pure number, to the nearest
0,1 mg and put into an empty and dry 50 ml volumetric flask, weighed before to the nearest 0,01 g. Add
40 ml of water and dissolve the MDU in an ultrasonic bath (6.4) for about 10 min (if necessary gently
warm). Make up approximately to the mark with water and homogenize. Weigh the full flask to the
nearest 0,01 g and record the net mass. Store at room temperature, well closed. This stock solution is
stable for three weeks.
8.1.3 Stock solution of dimethylen-triurea, ρ ≈ 1 000 mg/kg
Weigh 50/P mg of DMTU (5.4), where P is the purity of DMTU expressed as a pure number, to the
nearest 0,1 mg and put into an empty and dry 50 ml volumetric flask, weighed before to the nearest
0,01 g. Add 40 ml of water at 60 °C and dissolve the DM
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