prEN 15475

SLOVENSKI STANDARD
01-marec-2026
Anorganska gnojila - Titrimetrijsko določanje amonijevega dušika
Inorganic fertilizers - Titrimetric determination of ammoniacal nitrogen
Anorganische Düngemittel - Titrimetrische Bestimmung von Ammoniumstickstoff
Engrais inorganiques - Dosage titrimétrique de l’azote ammoniacal
Ta slovenski standard je istoveten z: prEN 15475
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
January 2026
ICS 65.080 Will supersede EN 15475:2009
English Version
Inorganic fertilizers - Titrimetric determination of
ammoniacal nitrogen
Engrais inorganiques - Dosage titrimétrique de l'azote Anorganische Düngemittel - Titrimetrische
ammoniacal Bestimmung von Ammoniumstickstoff
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 15475:2026 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
6 Apparatus . 6
7 Sampling and sample preparation . 11
7.1 Sampling . 11
7.2 Sample preparation . 11
8 Procedure . 11
8.1 Preparation of the sample solution . 11
8.1.1 General. 11
8.1.2 Direct weighing without sample dissolution . 11
8.2 Distillation of the sample solution. 11
8.3 Titration of the sample solution . 12
8.4 Blank . 14
8.5 Control test . 14
9 Calculation and expression of the result . 14
10 Precision . 14
10.1 Inter-laboratory test . 14
10.2 Repeatability . 14
10.3 Reproducibility . 15
11 Test report . 15
Annex A (informative) Results of the inter-laboratory tests . 16
Bibliography . 17

European foreword
This document (prEN 15475:2026) 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 will supersede EN 15475:2009.
a) measurement principle added to title;
b) normative references revised;
c) references to Regulation (EC) No 2003/2003 removed;
d) specifications for water revised;
e) reagents and apparatus revised;
f) explanatory notes added.
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 titrimetric determination of the ammoniacal nitrogen content
in inorganic fertilizers (including compound fertilizers), in which nitrogen is found exclusively either in
the form of ammonium salts or ammonium salts together with nitrates.
This document is applicable to the fertilizing products blends where a blend is a mix of at least two of the
following components: fertilizers, liming materials, soil improvers, growing media, inhibitors, plant
biostimulants and where the following category: inorganic fertilizers is the highest % in the blend by
mass or volume, or in the case of liquid form by dry mass. If inorganic fertilizers are not the highest % in
the blend, the European Standard for the highest % of the blend applies. In case a fertilizing product blend
is composed of components in equal quantity, the user decides which standard to apply. Variations in
analytical methods for fertilizing product blends can lead to differing results as some components or
matrix interactions can affect the outcome. Validation procedures have shown that developed standard
methods are robust and reliable across diverse product compositions, but possible interferences and
unexpected results when analysing fertilizing product blends are possible.
In the case of application to ammonium nitrate fertilizers of high nitrogen content, this document is not
applicable to fertilizer product blends.
This document is not applicable to fertilizers or fertilizer product blends containing urea, cyanamide,
nutrient polymers or other organic nitrogenous compounds.
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
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 terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https://www.iso.org/obp
— IEC Electropedia: available at https://www.electropedia.org/
4 Principle
An excess of sodium hydroxide solution is added to the sample. This converts the ammoniacal nitrogen
contained into ammonia, which is transferred into a known volume of sulphuric acid standard solution
by distillation. The excess acid is determined by titration with sodium hydroxide or potassium hydroxide
standard solution.
5 Reagents
Use only reagents of recognized analytical grade.
5.1 Water. The electrical conductivity of distilled or demineralized water used in the analysis shall at
least be < 0,5 mS/m (at 25 °C).
5.2 Hydrochloric acid, c = 12 mol/l, w = 37 %, ρ20 °C = 1,18 g/ml.
°C = 1,10 g/ml.
5.3 Hydrochloric acid solution, c = 6 mol/l, w = 20 %, ρ20
In a fume cupboard, transfer 500 mL of hydrochloric acid (5.2) into a 1000 mL volumetric flask and dilute
to the mark with water.
5.4 Sulfuric acid standard solution, c = 0,05 mol/l.
For variant a, see 8.3.
5.5 Sodium or potassium hydroxide standard solution, c = 0,1 mol/l, carbonate free.
For variant a, see 8.3.
5.6 Sulfuric acid standard solution, c = 0,1 mol/l.
For variant b, see 8.3.
5.7 Sodium or potassium hydroxide standard solution, c = 0,2 mol/l, carbonate free.
For variant b, see 8.3.
5.8 Sulfuric acid standard solution, c = 0,25 mol/l.
For variant c, see 8.3.
5.9 Sodium or potassium hydroxide standard solution, c = 0,5 mol/l, carbonate free.
For variant c, see 8.3.
5.10 Concentrated sodium hydroxide solution, c = 10 mol/l, w = 30 %, ρ °C = 1,33 g/ml, ammonia
free.
5.11 Methyl red.
5.12 Methylene blue.
5.13 Ethanol, φ = 95 %.
5.14 Indicator solutions.
5.14.1 Mixed indicator.
Solution A: Dissolve 1 g of methyl red (5.11) in 37 ml of sodium hydroxide solution (5.5) and make up
to 1 l with water.
Solution B: Dissolve 1 g of methylene blue (5.12) in water and make up to 1 l.
Mix one volume of A with two volumes of B.
This indicator is violet in acid solution, grey in neutral solution and green in alkaline solution. Use 0,5 ml
(10 drops) of this indicator solution.
5.14.2 Methyl red indicator solution.
Dissolve 0,1 g of methyl red (5.11) in 50 ml of ethanol (5.13). Make up to 100 ml with water and filter if
necessary. This indicator may be used (4 to 5 drops) instead of the preceding one. This indicator is red in
acid solution and yellow in alkaline solution.
5.15 Ammonium sulfate.
6 Apparatus
6.1 Balance, with a readability of ≤ 0,001 g.
6.2 Graduated flasks, capacity 500 ml.
6.3 Pipettes, capacity of 10 ml, 20 ml, 25 ml, 50 ml, 100 ml and 200 ml.
6.4 Rotary shaker, 35 to 40 r/min.
6.5 Filter, free of nitrogen, e.g. 100 % cellulose
6.6 Distillation apparatus.
Consisting of a round-bottomed flask of suitable capacity connected to a condenser by means of a splash
head. The equipment is made of borosilicate glass.
Figures 1 to 4 show possible different types of equipment for this determination via non-automated
distillation, including all construction features.
Alternatively, automated distillation and/or titration apparatuses equipped with sensors for photometric
determination or with pH electrodes for potentiometric determination may be used. The operator shall
demonstrate, by means of statistically equivalent results, that the automated devices comply with the
precision criteria specified in Annex A. The operation shall comply with the necessary safety precautions
and the corresponding user manuals, including the precautions required to avoid ammonia loss.
6.7 Anti-bump granules, i.e. pumice stone, glass pearls, washed in hydrochloric acid and calcined.
Dimensions in millimetres
Key
1 round-bottomed, long-necked flask of 1 000 ml capacity
2 distillation tube with a splash head, connected to the condenser by means of a spherical joint (No 18) (the
spherical joint for the connection to the condenser may be replaced by an appropriate rubber connection)
3 funnel with a polytetrafluoroethylene (PTFE) tap (6) for the addition of sodium hydroxide
4 six-bulb condenser with spherical joint (No 18) at the entrance, and joined at the issue to a glass extension
tube by means of a small rubber connection (when the connection to the distillation tube is effected by means of a
rubber tube, the spherical joint may be replaced by a suitable rubber bung)
5 500-ml-flask in which the distillate is collected
6 PTFE-tap (the tap may l
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