oSIST prEN ISO 25705:2019

SLOVENSKI STANDARD
01-junij-2019
Gnojila - Določevanje kondenzatov sečnine s tekočinsko kromatografijo visoke
ločljivosti (HPLC) - Izobutilidendiurea in krotonilidendiurea (metoda A) in oligomeri
metilenuree (metoda B) (ISO 25705:2016)
Fertilizers - Determination of urea condensates using high-performance liquid
chromatography (HPLC) - Isobutylidenediurea and crotonylidenediurea (method A) and
methylene-urea oligomers (method B) (ISO 25705:2016)
Düngemittel - Bestimmung von Harnstoffkondensaten mit Hochleistungs-
Flüssigchromatographie (HPLC) - Isobutylidendiharnstoff und Crotonylidendiharnstoff
(Verfahren A) und Methylenharnstoff-Oligomere (Verfahren B); Deutsche und Englische
Fassung prEN ISO 25705:2018
Engrais - Dosage des condensats d'urée par chromatographie liquide haute
performance (HPLC) - Isobutylidène diurée et crotonylidène diurée (méthode A) et
oligomères de méthylène-urée (méthode B) (ISO 25705:2016)
Ta slovenski standard je istoveten z: prEN ISO 25705
ICS:
65.080 Gnojila Fertilizers
71.040.50 Fizikalnokemijske analitske Physicochemical methods of
metode analysis
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

INTERNATIONAL ISO
STANDARD 25705
First edition
2016-04-01
Fertilizers — Determination of
urea condensates using high-
performance liquid chromatography
(HPLC) — Isobutylidenediurea and
crotonylidenediurea (method A) and
methylen-urea oligomers (method B)
Engrais — Dosage des condensats d’urée par chromatographie
liquide haute performance (CLHP) — Isobutylidène diurée et
crotonylidène diurée (méthode A) et oligomères de méthylène-urée
(méthode B)
Reference number
ISO 25705:2016(E)
©
ISO 2016
ISO 25705:2016(E)
© ISO 2016, Published in Switzerland
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ii © ISO 2016 – All rights reserved

ISO 25705:2016(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Sampling and sample preparation . 1
5 Method A: Determination of CDU and IBDU . 1
5.1 Principle . 1
5.2 Reagents. 1
5.3 Apparatus . 2
5.4 Procedure . 2
5.4.1 System parameters of HPLC . 2
5.4.2 Calibration . 2
5.4.3 Preparation of the test portion . 3
5.4.4 Measurement . 3
5.4.5 Important annotations . 3
5.5 Calculation . 3
6 Method B: Determination of methylene-urea oligomers (MU) . 4
6.1 Principle . 4
6.2 Reagents. 4
6.3 Apparatus . 4
6.4 Procedure . 5
6.4.1 System parameters of HPLC . 5
6.4.2 Calibration . 5
6.4.3 Preparation of the test solution . 6
6.4.4 Measurement . 7
6.4.5 Important annotations . 7
6.5 Calculations . 7
7 Precision method A and method B . 8
7.1 Inter-laboratory test. 8
7.2 Repeatability . 8
7.3 Reproducibility . 8
8 Test report . 9
Annex A (informative) Results of the inter-laboratory tests .10
Annex B (informative) Chromatogram and calibration curves method A .12
Annex C (informative) Chromatogram and calibration curves method B.14
Bibliography .17
ISO 25705:2016(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www.iso.org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation on the meaning of ISO specific terms and expressions related to conformity
assessment, as well as information about ISO’s adherence to the WTO principles in the Technical
Barriers to Trade (TBT) see the following URL: Foreword - Supplementary information
ISO 25705 was prepared by CEN/TC 260 (as EN 15705:2010) and was adopted by Technical Committee
ISO/TC 134, Fertilizers and soil conditioners. The following modifications were made.
— The references to EN 1482-1 and EN 1482-2 were changed to ISO 14820-1 and ISO 14820-2.
— In 5.2.1 and 6.2.1, the general text (not related to the water) was moved directly under 5.2 and 6.2,
respectively.
— In Table 1, the word “approximate” was added to the column headers for IBDU and CDU.
— In 5.4.3 and 6.4.3, “the sample grounded” was changed to “the ground sample”.
— In 6.4.3, “pieces of glass” and “pieces” were replaced by “boiling stones”.
— In 6.4.2.1, 6.4.2.2, 6.4.2.3, and 6.4.2.4, “by placing the flask in the” was added before “ultrasonic bath”.
— In 6.4.2.1, 6.4.2.2, 6.4.2.3, 6.4.2.4, 6.4.2.5 and 6.4.3, “homogenize” was changed to “mix thoroughly”.
— In 6.4.2.5, “before transferring into” was changed to “before transferring in” three times.
— In the keys for Figures B.2, B.3, B.4, C.2, C.3, C.4 and C.5, the units for the areas were added.
iv © ISO 2016 – All rights reserved

ISO 25705:2016(E)
Introduction
Fertilizers containing the condensates of urea and specified aldehydes (with crotonaldehyde called
crotonyliden diurea or CDU, with isobutyraldehyde called isobutylidene diurea or IBDU, with
formaldehyde called urea formaldehyde or methylene urea or MU) are covered by Regulation (EC)
[4]
2003/2003, Annex I as nitrogenous fertilizers. The methods described in this International Standard
enable the quantitative determination of these condensates and the determination of the solubility of
the MU-oligomers according to the Regulation.
INTERNATIONAL STANDARD ISO 25705:2016(E)
Fertilizers — Determination of urea condensates using
high-performance liquid chromatography (HPLC) —
Isobutylidenediurea and crotonylidenediurea (method A)
and methylen-urea oligomers (method B)
1 Scope
This International Standard specifies methods for the determination of isobutylidene diurea (IBDU),
Crotonylidene diurea (CDU) (method A) and methylene-urea oligomers (MU) (method B) in fertilizers
using high-performance liquid chromatography (HPLC).
The method is applicable to all fertilizers which do not contain interfering organic compounds.
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.
ISO 3696, Water for analytical laboratory use — Specification and test methods
ISO 14820-2, 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
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 Sampling and sample preparation
Sampling is not part of the method specified in this International Standard. A recommended sampling
method is given in ISO 14820-1.
Sample preparation shall be carried out in accordance with ISO 14820-2.
5 Method A: Determination of CDU and IBDU
5.1 Principle
The sample is extracted with water and, after appropriate dilution, analysed using a suitable HPLC system.
5.2 Reagents
Use only reagents of recognized analytical grade, unless otherwise specified.
5.2.1 Water, distilled or demineralized water (grade 3 according to ISO 3696).
ISO 25705:2016(E)
5.2.2 Acetonitrile, HPLC-grade.
5.2.3 Isobutylidene diurea and Crotonylidene diurea, in their pure form.
5.3 Apparatus
5.3.1 Laboratory equipment and glassware, for preparation of solutions and dilutions.
5.3.2 Analytical balance, capable of weighing to an accuracy of ±0,1 mg.
5.3.3 HPLC-system, with UV-detector.
5.3.4 Ultrasonic bath.
5.3.5 Magnetic stirrer.
5.3.6 Disposable filter, 0,45 μm.
5.4 Procedure
5.4.1 System parameters of HPLC
1)
Analytical/separating column:    silica column with C18 reverse phase
Detection wavelength: 200 nm
Eluent: acetonitrile/water: 10/90 (volume fraction)
Flow rate: 1 ml/min
Temperature: ambient temperature
Injection volume: 20 μl
5.4.2 Calibration
5.4.2.1 Stock solution IBDU ρ(IBDU) = 100 mg/l
Weigh 100/R mg of IBDU (5.2.3), where R is the purity of IBDU, into a 1 000 ml flask and add about
900 ml of water (5.2.1). Dissolve in an ultrasonic bath (5.3.4) for about 10 min, followed by stirring on a
magnetic stirrer (5.3.5) for about 1 h. Make up to volume. Filtration is not necessary.
5.4.2.2 Stock solution CDU ρ(CDU) = 100 mg/l
Weigh 100/R mg of CDU (5.2.3), where R is the purity of CDU, into a 1 000 ml flask and add about
900 ml of water (5.2.1). Dissolve in an ultrasonic bath (5.3.4) for about 10 min, followed by stirring on a
magnetic stirrer (5.3.5) for about 1 h. Make up to volume. Filtration is not necessary.
5.4.2.3 Calibration solution
For calibration, prepare three solutions according to Table 1 using one-mark (bulb) pipettes and dilute
to the mark with water (5.2.1).
1) LiChrosorb RP-18 7 µm 250/4 mm is an example of a suitable product available commercially. This information
is given for the convenience of users of this International Standard and does not constitute an endorsement by ISO
of this product.
2 © ISO 2016 – All rights reserved

ISO 25705:2016(E)
For the determination of the retention time, dilute 10 ml of the stock solution (5.4.2.1) or respectively
(5.4.2.2) into two 100 ml flasks and make up to volume with water (5.2.1).
The evaluation of calibration is carried out manually or by means of a suitable PC-aided (computerized)
calculation method.
Table 1 — Preparation of calibration solutions
Parameter Amount of stock Content of IBDU Content of CDU
solution IBDU/CDU mg/l mg/l
ml
(approximate) (approximate)
(to be added to the
100 ml flask)
Standard 1 10 10,0 10,0
Standard 2 25 25,0 25,0
Standard 3 50 50,0 50,0
5.4.3 Preparation of the test portion
Weigh 1 g of the ground sample to <0,2 mm to the nearest 0,1 mg and quantitatively transfer into a
1 000 ml volumetric flask with water (5.2.1). Fill the flask to an amount of approximately 900 ml and
treat it for 10 min in the ultrasonic bath (5.3.4). Then make up to the mark and stir for 1 h at room
temperature on a magnetic stirrer (5.3.5). Dilute 10 ml of the solution in a 100 ml volumetric flask and
filter into the HPLC injection vial through a disposable filter (5.3.6).
5.4.4 Measurement
Measurement is performed manually or by means of an automatic sample loading system (autosampler).
5.4.5 Important annotations
IBDU is able to form urea in aqueous solution. Therefore, the measurement of the calibration and sample
solutions shall be completed within one working day.
The concentrations of CDU and IBDU in the sample solutions shall be kept within the calibration limits
(5.4.2) to ensure sufficient reproducibility.
5.5 Calculation
The calculation can be performed manually or by means of a PC using the calibration parameters in
respect to the amount used.
In the case of PC-aided (computerized) calculation and application of Table 1 regarding the amounts of
stock solution, the
...