prEN 18317

Organo-mineral fertilizers - Determination of the N-(n-butyl)thiophosphoric triamide (NBPT) urease inhibitor content

This document specifies a method for the determination of the urease inhibitor
N-(n-butyl)thiophosphoric triamide (NBPT) and its oxidate form N-(n-butyl)phosphoric triamide (NBPTO) in urea based organo-mineral fertilizers, using the liquid chromatography coupled with triple quadrupole mass spectrometry (LC-MSQQQ).
This document is applicable to organo-mineral fertilizers.
NOTE   It is possible to apply this method to inorganic fertilizers; in this case a validation is carried out by the laboratory for the procedure and data generated.

Organisch-mineralische Düngemittel - Bestimmung des Gehaltes an Ureasehemmstoff

Dieses Dokument legt ein Verfahren zur Bestimmung des Urease-Hemmstoffs N (n Butyl) thiophosphortriamid (NBPT) und seiner Oxidationsform N (n Butyl)-phosphortriamid (NBPTO) in organisch-mineralischen Düngemitteln auf Harnstoffbasis mittels Flüssigkeitschromatographie gekoppelt mit Triple-Quadrupol-Massenspektrometrie (LC MSQQQ) fest.
Dieses Dokument ist auf organisch-mineralische Düngemittel anwendbar.
ANMERKUNG   Eine Anwendung des Verfahrens auf anorganische Düngemittel ist möglich; in diesem Fall führt das Labor eine Validierung des Verfahrens und der erzeugten Daten durch.

Engrais organo-minéraux - Détermination de la teneur en inhibiteur d’uréase N-(n-butyl) triamide thiophosphorique (NBPT)

Le présent document spécifie une méthode pour le dosage de l’inhibiteur d’uréase N-(n-butyl) triamide thiophosphorique (NBPT) et du N-(n-butyl) triamide phosphorique sous sa forme oxydée (NBPTO) dans des engrais organo-minéraux à base d’urée, en utilisant la chromatographie liquide couplée à la spectrométrie de masse à triple quadripôle (LC-MSQQQ).
Le présent document est applicable aux engrais organo-minéraux.
NOTE   Il est possible d’appliquer cette méthode aux engrais inorganiques; dans ce cas, une validation est réalisée par le laboratoire pour le mode opératoire et les données générées.

Organsko-mineralna gnojila - Določanje inhibitorja ureaza N-(n-butil)tiofosfortriamida (NBPT)

General Information

• Status: Not Published
• Publication Date: 28-Feb-2028
• ICS: 65.080 - Fertilizers
• Technical Committee: CEN/TC 260 - Fertilizers and liming materials
• Drafting Committee: CEN/TC 260/WG 7 - Chemical analysis
• Current Stage: 4020 - Submission to enquiry - Enquiry
• Start Date: 19-Feb-2026
• Due Date: 13-Oct-2026
• Completion Date: 19-Feb-2026
• Directive: Not Harmonized2019/1009 - Regulation (EU) 2019/1009 of the European Parliament and of the Council of 5 June 2019 laying down rules on the making available on the market of EU fertilising products and amending Regulations (EC) No 1069/2009 and (EC) No 1107/2009 and repealing Regulation (EC) No 2003/2003 (Text with EEA relevance)
• Mandate: M/564 - Fertilising products in support of Regulation (EU) 2019/1009
• Mandate: M/564 AMD 1 - amending Implementing Decision C(2020) 612 as regards certain harmonised standards and standardisation deliverables, deadlines for their adoption and the duration of the validity of the standardisation request
• Mandate: M/564 AMD 2 - Commission Implementing decision amending Implementing Decision C(2020)612 as regards harmonised standards, the deadlines for the adoption of those standards and the duration of the validity of the standardisation request to the European Committee for Standardisation as regards the EU fertilising products in support of Regulation (EU) 2019/1009 of the European Parliament and of the Council
• Ref Project: oSIST prEN 18317:2026 - Organo-mineral fertilizers - Determination of the N-(n-butyl)thiophosphoric triamide (NBPT) urease inhibitor content

Standards Content (Sample)

SLOVENSKI STANDARD
01-april-2026
Organsko-mineralna gnojila - Določanje inhibitorja ureaza N-(n-
butil)tiofosfortriamida (NBPT)
Organo-mineral fertilizers - Determination of the N-(n-butyl)thiophosphoric triamide
(NBPT) urease inhibitor content
Organisch-mineralische Düngemittel - Bestimmung des Gehaltes an Ureasehemmstoff
Engrais organo-minéraux - Détermination de la teneur en inhibiteur d’uréase N-(n-butyl)
triamide thiophosphorique (NBPT)
Ta slovenski standard je istoveten z: prEN 18317
ICS:
65.080 Gnojila Fertilizers
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

DRAFT
EUROPEAN STANDARD
NORME EUROPÉENNE
EUROPÄISCHE NORM
February 2026
ICS 65.080
English Version
Organo-mineral fertilizers - Determination of the N-(n-
butyl)thiophosphoric triamide (NBPT) urease inhibitor
content
Engrais organo-minéraux - Détermination de la teneur Organisch-mineralische Düngemittel - Bestimmung des
en inhibiteur d'uréase N-(n-butyl) triamide Gehaltes an Ureasehemmstoff
thiophosphorique (NBPT)
This draft European Standard is submitted to CEN members for enquiry. It has been drawn up by the Technical Committee
CEN/TC 260.
If this draft becomes a European Standard, 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.

This draft European Standard was established by CEN 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.
Recipients of this draft are invited to submit, with their comments, notification of any relevant patent rights of which they are
aware and to provide supporting documentation.

Warning : This document is not a European Standard. It is distributed for review and comments. It is subject to change without
notice and shall not be referred to as a European Standard.

EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2026 CEN All rights of exploitation in any form and by any means reserved Ref. No. prEN 18317:2026 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 . 5
5.1 General. 5
5.2 Reagents for liquid chromatography . 5
5.3 Calibration standards . 5
6 Equipment and consumables . 5
7 Sampling and sample preparation . 7
7.1 Sampling . 7
7.2 Sample preparation . 7
8 Procedure . 7
8.1 General. 7
8.2 Preparation of the test portion . 7
8.3 Calibration . 7
8.4 Blank test . 8
9 Calculation and expression of the result . 8
10 Precision . 9
10.1 Inter-laboratory study . 9
10.2 Repeatability . 9
10.3 Reproducibility . 9
10.4 NBPT Stability test . 10
11 Test report . 10
Annex A (informative) Results of the inter-laboratory study . 12
A.1 Inter-laboratory study . 12
A.2 Statistical results for the determination of NBPT and NBPTO by LC-MSQQQ . 13
Annex B (informative) Stability test of NBPT in organo-mineral fertilizers . 16
B.1 Stability test description . 16
Bibliography . 19

European foreword
This document (prEN 18317:2026) has been prepared by Technical Committee CEN/TC 260 “Fertilizers
and liming materials”, the secretariat of which is held by DIN.
This document is currently submitted to CEN Enquiry.
This document has been prepared under a standardization request addressed to CEN by the European
Commission. The Standing Committee of the EFTA States subsequently approves these requests for its
Member States.
1 Scope
This document specifies a method for the determination of the urease inhibitor
N-(n-butyl)thiophosphoric triamide (NBPT) and its oxidate form N-(n-butyl)phosphoric triamide
(NBPTO) in urea based organo-mineral fertilizers, using the liquid chromatography coupled with triple
quadrupole mass spectrometry (LC-MSQQQ).
This document is applicable to organo-mineral fertilizers.
NOTE It is possible to apply this method to inorganic fertilizers; in this case a validation is carried out by the
laboratory for the procedure and data generated.
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, liming materials and inhibitors — Sampling and sample preparation — Part 2:
General sample preparation provisions
prEN 12944-1, Fertilizers, liming materials and inhibitors — Vocabulary — Part 1: General terms
prEN 12944-2, Fertilizers, liming materials and inhibitors — Vocabulary — Part 2: Terms relating to
fertilizers
3 Terms and definitions
For the purposes of this document, the terms and definitions given in prEN 12944-1 and prEN 12944-2
and the following shall be applied.
ISO and IEC maintain terminology 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
This analytical method is based on the principles of liquid chromatography coupled with triple
quadrupole mass spectrometry (LC-MSQQQ) for determination of the separated inhibiting compounds
NBPT and NBPTO.
WARNING — Persons using this document should be familiar with normal laboratory practice. This
document does not purport to address all of the safety problems, if any, associated with its use. It is the
responsibility of the user to establish appropriate safety and health practices and to ensure compliance
with any national regulatory conditions.
IMPORTANT — It is absolutely essential that tests conducted in accordance with this document be
carried out by suitably trained staff.
5 Reagents
5.1 General
Use only reagents of recognized analytical grade and distilled water or ultrapure water for LC-MS.
5.2 Reagents for liquid chromatography
5.2.1 Methanol, LC-MS grade.
5.2.2 Formic acid, LC-MS grade.
5.2.3 Ammonium formate, p.a. high purity.
5.2.4 Water, ultrapure LC-MS grade or distilled water.
5.2.5 N-(n-butyl)thiophosphoric triamide (NBPT), CAS n. 94317-64-3, minimum mass fraction of
98 %.
5.2.6 N-(n-butyl)phosphoric triamide (NBPTO), CAS n. 25316-39-6, minimum mass fraction of
80 %.
5.2.7 Urea, p.a. high purity.
5.3 Calibration standards
5.3.1 Stock solution, mass concentration ρ = 0,20 mg/ml.
NBPT
Weigh 50 mg NBPT (5.2.5) into a 250 ml volumetric glass flask and dissolve to volume with water (5.2.4).
Store at +4 °C ± 1 °C for no more than 2 days.
5.3.2 Stock solution, ρ = 0,20 mg/ml.
NBPTO
Weigh 50 mg NBPTO (5.2.6) into a 250 ml volumetric glass flask and dissolve to volume with water
(5.2.4). Store at +4 °C ± 1 °C for no more than 2 days.
5.3.3 Blank solution, water (5.2.4).
6 Equipment and consumables
Disposable equipment is acceptable in the same way as reusable glassware if the specifications are
similar. Ordinary laboratory equipment, and particularly the following shall be used.
6.1 Analytical scale, capable of weighing to the nearest 0,000 1 g.
6.2 Graduated pipettes, for volumes 5 ml, 10 ml, 15 ml, 20 ml, 25 ml with an accuracy of 0,01 ml.
6.3 One-mark volumetric glass flasks Class A [3], capacity 100 ml and 250 ml.
6.4 Horizontal shaker agitator.
6.5 Qualitative filter paper.
6.6 LC-MSQQQ.
6.6.1 Operative conditions
— Column: a non-endcapped silica-based HSS PFP/Fluoro-Phenyl reversed phase HPLC column, 3,5 μm
4,6 mm × 150 mm (designed for low pH separations that require alternative selectivity compared to
a fully endcapped, high coverage C18 phase, usable for UPLC separations)
— Mobile phase A: Water (5.2.4) with 0,1 % formic acid (5.2.2) and 5 mmol ammonium formate (5.2.3)
— Mobile phase B: methanol (5.2.1) with 0,1 % formic acid (5.2.2)
— Mobile phases working gradient: see Table 1
— Flow rate: 0,6 mL/min
— Column temperature: 30 °C
— Injection volume: 20 μL
— Run time: 15 min
— Expected Retention Time, t of NBPT: 8 min.
R
— Expected Retention Time, t of NBPTO: 6,9 min.
R
Table 1 — Mobile phases working gradient
Gradient Mobile Mobile
time phase A phase B
min % %
0 90 10
2 90 10
7 5 95
10 5 95
10,1 90 10
15 90 10
— Detector: MS triple quadrupole (MSQQQ)
— Electrospray ionization (ESI)
— Positive polarity
— Gas temperature: 135 °C
— Gas flow: 12 l/min
— VCap: 4 000 V
— NBPT and NBPTO MSQQQ setting are in Table 2 and Table 3

Table 2 — NBPT MSQQQ setting
Collision
NBPT Molecular ion Fragment ion
energy
Qualifier 168 151 15
Quantifier 168 74 15
Table 3 — NBPTO MSQQQ setting
Collision
NBPT-O Molecular ion Fragment ion
energy
Qualifier 152 135.3 10
Quantifier 152 74.3 15
7 Sampling and sample preparation
7.1 Sampling
Sampling is not part of the method specified in this document. Recommended sampling methods are
given in EN 1482-1 [11] and EN 1482-3 [12].
It is important that the laboratory receives a sample that is representative of both the product under
consideration and the given analysis. The sample should not have been damaged or changed during
transport or storage.
7.2 Sample preparation
Sample preparation shall be carried out in accordance with EN 1482-2.
8 Procedure
8.1 General
8.2 Preparation of the test portion
An amount of 5 g of the test sample shall be weighted to the nearest 0,000 1 g, transferred to a 250 ml
volumetric glass flask (6.3), added a volume of 150 ml of water (5.2.4) and dissolved by shaking with
agitator (6.4) for 30 min at a rate that keeps the sample in suspension.
It shall be made up to volume with water, homogenized thoroughly and filtered with filter paper (6.5).
An aliquot portion of the extract in water (5.2.4) shall be diluted in one or more steps so that the final
concentration of the molecules to be determined falls within the calibration range (see 8.3).
All samples shall be injected in duplicate.
8.3 Calibration
Calibration shall be performed before the analysis.
Calibration curve shall include at least 5 calibration points chosen according to the sensitivity of the
available instrument.
The solutions shall be prepared at the time of each batch of analytical determination.
The stock solutions (5.3.1 and 5.3.2) shall be used to dete
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