Determination of urea content in urea-based fertilizers by high performance liquid chromatography (HPLC)

ISO 19746:2017 specifies the test procedure for determining the urea content in urea-based fertilizers, including urea, urea aldehydes [methylene urea fertilizers, isobutylene diurea (IBDU), crotonylidene diurea (CDU)], urea triazone fertilizers, urea ammonium nitrate (UAN), sulfur- and polymer-coated urea (SCU and PCU), as well as compound fertilizers containing urea. The method is based on High Performance Liquid Chromatography (HPLC). The proposed method is an extension of the AOAC Official Method 2003.14 which was collaboratively studied for the "Determination of Urea in Water-Soluble Urea-Formaldehyde Fertilizer Products and in Aqueous Urea Solutions" in 2003. The method was published in the Journal of AOAC in 2004[4] and was granted the First Action in 2003 and the Final Action in 2008. This method also applies to the determination of biuret content in urea containing fertilizer with the results published in the J. AOAC in 2014[5]. This method was adopted by the International Organization for Standardization (ISO) as a Committee Draft (ISO/CD 18643) in 2014, and after review and the Ring Test Analyses[6].

Détermination de la teneur en urée dans les engrais à base d'urée par chromatographie liquide à haute performance (CLHP)

General Information

Status
Published
Publication Date
22-Feb-2017
Current Stage
6060 - International Standard published
Start Date
29-Dec-2016
Completion Date
23-Feb-2017
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ISO 19746:2017 - Determination of urea content in urea-based fertilizers by high performance liquid chromatography (HPLC)
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INTERNATIONAL ISO
STANDARD 19746
First edition
2017-02
Determination of urea content in urea-
based fertilizers by high performance
liquid chromatography (HPLC)
Détermination de la teneur en urée dans les engrais à base d’urée par
chromatographie liquide à haute performance (CLHP)
Reference number
ISO 19746:2017(E)
ISO 2017
---------------------- Page: 1 ----------------------
ISO 19746:2017(E)
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© ISO 2017, Published in Switzerland

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ii © ISO 2017 – All rights reserved
---------------------- Page: 2 ----------------------
ISO 19746:2017(E)
Contents Page

Foreword ........................................................................................................................................................................................................................................iv

Introduction ..................................................................................................................................................................................................................................v

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ...................................................................................................................................................................................... 1

3 Terms and definitions ..................................................................................................................................................................................... 1

4 Principles ..................................................................................................................................................................................................................... 1

5 Reagents ........................................................................................................................................................................................................................ 1

6 Apparatus ..................................................................................................................................................................................................................... 2

7 Procedures .................................................................................................................................................................................................................. 2

7.1 Preparation of test sample ............................................................................................................................................................ 2

7.2 Preparation of the test solution ................................................................................................................................................ 2

7.3 Preparation of urea working standard solution ......................................................................................................... 3

7.4 HPLC conditions ..................................................................................................................................................................................... 3

7.5 Preparation of standard curve ................................................................................................................................................... 3

7.6 Determination of the urea content in the test solution ......... ............................................................................... 4

7.7 Calculation and expression of results.................................................................................................................................. 4

7.8 Precision ....................................................................................................................................................................................................... 4

7.8.1 Repeatability, r ................................................................................................................................................................. 4

7.8.2 Reproducibility, R ........................................................................................................................................................... 4

7.9 Test report ................................................................................................................................................................................................... 4

Annex A (informative) Examples of the retention times of triuret, biuret, urea and some

other ureaforms .................................................................................................................................................................................................... 5

Bibliography ................................................................................................................................................................................................................................ 8

© ISO 2017 – All rights reserved iii
---------------------- Page: 3 ----------------------
ISO 19746:2017(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

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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

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on the ISO list of patent declarations received (see www .iso .org/ patents).

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URL: w w w . i s o .org/ iso/ foreword .html.

This document was prepared by Technical Committee ISO/TC 134, Fertilizers and soil conditioners.

iv © ISO 2017 – All rights reserved
---------------------- Page: 4 ----------------------
ISO 19746:2017(E)
Introduction

Urea is the most widely used source of nitrogen fertilizers worldwide and is used in a variety of

forms such as pure urea, in combination with other nutrients, in complex fertilizers, and as reacted or

[2]
modified ureas .
[3]

Due to the rapid hydrolysis of urea in the environment, especially when applied at the soil surface ,

efforts have been made to modify urea to slow down this loss process. Slow release nitrogen fertilizers

such as methylene urea compounds, controlled release N fertilizers such as sulfur-coated urea (SCU)

or polymer-coated urea (PCU), and stabilized N fertilizers containing additives (urease inhibitors and

nitrification inhibitors) are examples of products aimed at containing the rapid hydrolyses of urea in

the soil.

Accurate determination of urea in urea-based fertilizers is desirable for regulatory and product

quality purposes. This is especially true for those fertilizers in which the urea content is physically or

chemically modified. Most of these modified fertilizers contain some amounts of free and unreacted

urea which is readily available N and therefore could not be accounted as part of the slow or controlled

[5]
release N component .
© ISO 2017 – All rights reserved v
---------------------- Page: 5 ----------------------
INTERNATIONAL STANDARD ISO 19746:2017(E)
Determination of urea content in urea-based fertilizers by
high performance liquid chromatography (HPLC)
1 Scope

This document specifies the test procedure for determining the urea content in urea-based fertilizers,

including urea, urea aldehydes [methylene urea fertilizers, isobutylene diurea (IBDU), crotonylidene

diurea (CDU)], urea triazone fertilizers, urea ammonium nitrate (UAN), sulfur- and polymer-coated

urea (SCU and PCU), as well as compound fertilizers containing urea. The method is based on High

Performance Liquid Chromatography (HPLC).

The proposed method is an extension of the AOAC Official Method 2003.14 which was collaboratively

studied for the “Determination of Urea in Water-Soluble Urea-Formaldehyde Fertilizer Products and in

[4]

Aqueous Urea Solutions” in 2003. The method was published in the Journal of AOAC in 2004 and was

granted the First Action in 2003 and the Final Action in 2008.

This method also applies to the determination of biuret content in urea containing fertilizer with the

[5]

results published in the J. AOAC in 2014 . This method was adopted by the International Organization

for Standardization (ISO) as a Committee Draft (ISO/CD 18643) in 2014, and after review and the Ring

[6]
Test Analyses .

NOTE This HPLC method can also be utilized to analyse Crotonylidene diurea (CDU) and Isobutylidene

[1]

diurea (IBDU) contents within those above-mentioned fertilizers, in addition to EN 15705 .

2 Normative references
The fo
...

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